Main achievements in 2022

approved by ISSP RAS Academic Board on December, 5, 2022
(protocol №26)

1. Realization of dynamic negative capacitance response in GeTe Rashba ferroelectric

N.N. Orlova, A.V. Timonina, N.N. Kolesnikov, E.V. Devyatov

Recently, observation of negative capacitance for various systems in order to increase the performance and energy efficiency of semiconductor devices is actively discussed.

We experimentally investigate capacitance response of GeTe ferroelectric with a giant spin-orbit interaction.

Unexpectedly, we observe a strong dependence of capacitance response on the gate field polarity, which is symmetrical to the polarity sign. Also, we observe well-developed hysteresis in capacitance response depending on the gate voltage sweep direction.

The capacitance behavior is explained by the dependence of the Rashba parameter on the gate electric field under conditions of constant carrier concentration in GeTe.

In this case, the hysteresis in C(V_g) should be ascribed to ferroelectric polarization evolution in GeTe surface layers, which also allows to realize the regime of dynamic negative capacitance in the sample, emerging when the ferroelectric polarization direction switches faster than the electric charge. The latter is independently verified by  time-dependent resistive measurements.

Publication: Orlova, N.N. Dynamic negative capacitance response in GeTe Rashba ferroelectric / N.N. Orlova, A.V. Timonina, N.N. Kolesnikov, E.V. Deviatov // Physica B: Condensed Matter. – 2022. – Vol. 647. – P. 414358. – DOI:10.1016/j.physb.2022.414358

State assignment “Collective phenomena in electron and exciton systems in nanostructures”

Physical Sciences, branch 1.3.2 "Physics of Condensed Media and Physical Materials Science".

2. Birotons and “dark” quantum Hall hierarchies

O.A. Grigorev, L.I. Musina, A.B. Van’kov, O.V. Volkov, L.V. Kulik

A computational scheme is suggested to estimate neutral excitation energies in the fractional quantum Hall effect (FQHE) states.

The FQHE states are systematized according to the Farey-number hierarchy structure.

It is shown that besides the widely known Laughlin–Jain hierarchy of fractional states, there exist other “dark” hierarchies.

Although hardly observed even in the highest mobility samples, they can significantly affect the thermodynamics and spectral characteristics of the FQHE states.

The known problems in the interpretation of FQHE’s experimental results are explained in terms of the coexistence of two fundamentally different transformation types of the electron system, one of which is a neutral excitation in the FQHE state, whereas the other is a transition between two FQHE ground states, one of which represents the Laughlin–Jain FQHE hierarchy and the other a state of “dark” hierarchies.

Fig. (a). Energies of birotons with zero momentum, in a magnetic field of 10 T, calculated for different FQHE states in the range of Coulomb energies from 0.001 to 0.1e²/ϵl_B . The fractional states of the Laughlin–Jain hierarchy and of the “dark” hierarchies are plotted in grey and red circles, respectively. (b) FQHE states with energies from (a) brought into the Zang–Birman hierarchical structure (Farey-number hierarchy structure). Horizontal and vertical axes denote, accordingly, the fraction’s absolute value and its denominator. The dot diameter is proportional to the energy of the biroton with zero momentum of the corresponding fraction. The lines link the fractional states of individual hierarchies.

Publication: Grigorev, O.A. Birotons and “Dark” Quantum Hall Hierarchies / O.A. Grigorev, L.I. Musina, A.B. Van’kov, O.V. Volkov, L.V. Kulik // Applied Sciences. – 2022. – Vol. 12, Iss. 15. – P. 7940. – DOI:10.3390/app12157940

RSF grant 18-12-00246

Physical Sciences, branch 1.3.2 "Physics of Condensed Media and Physical Materials Science".

3. Ultrafast all-optical intensity and polarization switch controlled by acoustic perturbation of multistable microcavity exciton-polariton systems

A.A. Demenev, S.S. Gavrilov, V.D. Kulakovskii et al.

Built-in switches are the basis for ultra-fast optical signal processing.

We investigate the possibility of realizing ultrafast signal switches based on multistable exciton-polariton condensates in planar microcavities on which resonant excitation by a photon energy slightly exceeding the lower polariton resonance is performed.

Stationary states of polariton condensate switching are studied on GaAs/AlAs-based high-Q microcavities with InGaAs quantum wells in the active region.

Subterahertz acoustic modulation of the polariton resonance is obtained by injecting into the microcavity picosecond strain pulses generated by 200 fs-long violet femtosecond laser pulses on the back side of the substrate.

It has been experimentally demonstrated that picosecond acoustic strain pulses can be used for controlled ultrafast (~100 ps) switching both between stationary states in a resonantly excited circularly polarized condensate, with radiation intensity switching by more than an order of magnitude, and between branches with different polarizations in an elliptically polarized condensate with a several times change in the value of the circularly polarized component.

Fig. (a) Temporal profiles of circular polarization degree in an elliptically polarized beam in the absence (black dashed curve) and when excited (red solid curve) with femtosecond pulse with W=0.8mJ/cm².
(b) and (c) Intensities of the right- (σ⁺⁾ and left- (σ^-) polarized components (red solid and black dotted curves, respectively) measured during resonant excitation of polaritons by elliptically polarized light with P=150kW/cm² in the absence (c) and during excitation by a purple femtosecond pulse with W = 0.8 mJ/cm² (b).
The arrow indicates excitation time of quantum wells by the acoustic pulse.
The time resolution in the measurements is 2 ns.

Publication: Demenev, A.A. Ultrafast All-Optical Polarization Switch Controlled by Optically Excited Picosecond Acoustic Perturbation of Exciton Resonance in Planar Microcavities / A.A. Demenev, D.D. Yaremkevich, A.V. Scherbakov, S.S. Gavrilov, D.R. Yakovlev, V.D. Kulakovskii, M. Bayer // Physical Review Applied. – 2022. – Vol. 18, Iss. 4. – P. 44045. – DOI:10.1103/PhysRevApplied.18.044045

RSF grant 21-12-00368

Physical Sciences, branch 1.3.2 "Physics of Condensed Media and Physical Materials Science".

4. Superresolution imaging using a tapered bundle of high-refractive-index optical fibers

G.M. Katyba, I.N. Dolganova, V.N. Kurlov et al.

Optical fiber bundles can be used to obtain images with resolution exceeding the Abbe limit.

Such bundles are based on 300 μm sapphire fiber which provide exceedingly good localization of THz radiation in the fiber core due to high refractive index in THz range and, therefore, high image resolution.

We develop, produce and characterize a tapered sapphire fibre bundle for subwavelength-resolution imaging.

The fibers diverge from the object plane (the output bundle) and, thus, stretch the captured near field for its further readout using conventional diffraction-limited lens.

Such a tapered fiber bundle is investigated numerically and then implemented experimentally at 0.33 THz. The developed imaging principle allows the Abbe resolution limit, the mid-value of which is 0.35 λ, where λ=917 μm, to be overcome.

Schematic of near-field imaging with a tapered fiber bundle (a); axial section of a cone-shaped bundle with geometric dimensions (b).

Publication: Katyba, G.M. Superresolution Imaging Using a Tapered Bundle of High-Refractive-Index Optical Fibers / G.M. Katyba, M. Skorobogatiy, D.G. Melikyants, N.V. Chernomyrdin, A.N. Perov, E.V. Yakovlev, I.N. Dolganova, I.E. Spektor, V.V. Tuchin, V.N. Kurlov, K.I. Zaytsev // Physical Review Applied. – 2022. – Vol. 18, Iss. 3. – P. 34069. – DOI:10.1103/PhysRevApplied.18.034069

RSF grant 22-72-10033

Physical Sciences, branch 1.3.5 “Optics and laser Physics”

5. Magnetic memory effect in planar ferromagnetic/superconductor/ferromagnetic microbridges

L.N. Karelina, N.S. Shuravin, A.S. Ionin, S.V. Egorov, V.V. Bolginov, V.V. Ryazanov et al.

We investigate the effect of negative magnetoresistance R(H) in a three-layer FSF microbridge based on superconducting niobium (S) and weakly ferromagnetic (F) Pd_0.99Fe_0.01alloy.

The remagnetization curves R(H) in the end of the temperature transition of the microbridge to the superconducting state show sharp minima of the S-layer resistance ("low-resistivity state") with opposite directions of the F-layers magnetization.

We find that this low-resistivity state has a memory effect, i.e., the value of R_min(H_min) actually does not change in some fields interval below H_min, as shown in Fig.1.

The descending (black) section of the loop also shows a slight increase in magnetoresistance associated with spin-triplet superconductivity in non-collinear F-layer magnetization directions, when "spin-triplet" superconducting carriers can go far into the F-layer (suppressing superconductivity in the S-layer ).

Figure 2 demonstrates the use of the detected effect as a memory element that changes its "digital" mode under a weak magnetic field pulse.

Fig.1.	Fig.2.

Publication: Magnetic memory effect in planar ferromagnetic/superconductor/ferromagnetic microbridges based on highly diluted PdFe alloy/ L.N. Karelina, N.S. Shuravin, A.S. Ionin, S.V. Bakursky, S.V. Egorov, I.A. Golovchansky, V.I. Chichkov, V.V. Bolginov, V.V. Ryazanov // JETP Letters – 2022. – Vol. 116, № 2. – P. 108–115. – DOI:10.31857/S1234567822140075 (in Ruissian)

RSF grant № 19-32-90162

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

6. Developing an industrial technology of producing three-layer membranes and anode supports for high-efficiency solid oxide fuel cells

E.A. Agarkova, D.A. Agarkov, I.N. Burmistrov, I.E. Kuritsyna, D.V. Yalovenko, S.I. Bredikhin

As a result of comprehensive studies of ionic conductivity, mechanical characteristics and formation features of multilayer gas-tight membranes based on anion conductor of stabilized ZrO₂, an industrial technology for manufacturing trilayer membranes of 6ScSZ|10Sc1YSZ|6ScSZ composition, sized 100x100 mm and 150 μm thick for first-generation high efficiency SOFCs is developed and introduced.

In May 2022 under technical specifications TS 23.44.12.190-193-30742093-2022 at JSC "NEVZ-CERAMICS" (Novosibirsk) production of three-layer membranes was launched, which are the basis of SOFC on the electrolyte carrier (see Figure 1).

In order to develop an industrial technology for manufacturing two-layer anode SOFC supports on a carrier anode, charge transfer processes, the course of redox reactions, and the mechanical characteristics of SOFC anodes are studied [1-2].

The industrial technology of manufacturing two-layer anode supports for second-generation SOFC has been created at "NEVZ-CERAMICS" (see Figure 2).

Figure 1. Trilayer 6ScSZ|10Sc1YSZ|6ScSZ anion conductor membranes sized 100x100 mm and 150 µm thick

Figure 2. Two-layer anode substrates for second-generation SOFCs, manufactured at "NEVZ-CERAMICS"

Publications:

1. Agarkova, E.A. Tape Casting of Bilayered Anode Supports and Electrochemical Performance of SOFCs Based on Them / E.A. Agarkova, O.Yu. Zadorozhnaya, I.N. Burmistrov, D.A. Agarkov, A.A. Solov’ev, A.V. Shipilova, M.N. Levin, Yu.K. Nepochatov, S.I. Bredikhin // Russian Journal of Electrochemistry. – 2022. – Vol. 58, Iss. 2. – P. 114–121. – DOI:10.1134/S1023193522020033

2. Solovyev, A.A. Influence of Deposition Modes and Thermal Annealing on Residual Stresses in Magnetron-Sputtered YSZ Membranes / A.A. Solovyev, S.V. Rabotkin, A.V Shipilova, D.A. Agarkov, I.N. Burmistrov, A.N. Shmakov // Membranes. – 2022. – Vol. 13, Iss. 2. – P. 346. – DOI:10.3390/membranes12030346

State assignment : "Physics, Technology, and Engineering of Defect Materials for Alternative Energy Sources, Photovoltaics, and Sensorics"

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

7. Functionalization of graphene on β-SiC/Si(001) wafers by molecules of phenazine Neutral Red dye

A.N. Chaika, V.Yu. Aristov et al.

The atomic and electron structure of graphene on β-SiC(001) layers has been functionalyzed with molecules of phenazine dye Neutral Red and studied with X-ray photoelectron spectroscopy, density functional theory, scanning tunneling microscopy (STM) and spectroscopy (STS).

According to scanning tunneling spectroscopy, the dye molecules form local short-range ordered structures on small areas of the surface and can be oriented both parallel and perpendicular to the graphene layers.

In the first case, the molecules form dimeric structures, while in the second, they form structures with a rectangular or oblique-angled unit cell.

It has been found that modification of the graphene upper layer leads to the appearance of the band gap exceeding 1 eV, which allows us to consider the synthesized layered composite a low-dimensional metal/semiconductor type heterostructure.

It is shown that local changes in the band gap width on the surface can be related to molecule deformations in the composite structure.

Fig. (a,b,e) STM images of graphene/SiC(001) system before (a) and after (b,e) functionalization by phenazine dye molecules. (c,d,f) Schematic arrangement of molecules on the graphene surface oriented perpendicular (c,d) and parallel (f) to the surface. (g) Experimental STS spectra measured at different surface areas. (h) Calculated density of electron states of molecules on graphene surface depending on molecule compression (0-15%).

Publication: Potorochin, D.V. Surface functionalization of few-layer graphene on β-SiC(001) by Neutral Red dye / D.V. Potorochin, A.N. Chaika, O.V. Molodtsova, V.Yu. Aristov, D.E. Marchenko, D.A. Smirnov, A.A. Makarova, B. Walls, K. Zhussupbekov, K. Walshe, I.V. Shvets, A.S. Ciobanu, M.K. Rabchinskii, N.V. Ulin, M.V. Baidakova, P.N. Brunkov, S.L. Molodtsov // Applied Surface Science. – 2022. – Vol. 585. – P. 152542. – DOI:10.1016/j.apsusc.2022.152542

State assignment: "Physics, Technology, and Engineering of Defect Materials for Alternative Energy Sources, Photovoltaics, and Sensorics"

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

8. Designing technological bases of monopolar metal-supported solid oxide fuel cells.

M.N. Levin, I.N. Burmistrov, A.U. Sharafutdinov, I.S. Yerilin et al.

Essence. The concept, structure and technology of Metal-Supported Monopolar Solid Oxide Fuel Cells – MMS-SOFC has been developed.

Novelty. The technological process of SOFC fabrication has been significantly simplified by reducing the number of technological operations and intermediate heat treatments, as a result of using impact aerosol deposition (AD) of the anode on high-relief porous metal supports, magnetron sputtering (MSP) of solid electrolyte and cathode stenciling with a single final annealing.

New monopolar designs have been proposed that provide a significant increase in gravimetric and volumetric power densities of SOFC metal-supported blocks.

Validity. The proposed technology is the basis for mass production of metal-supported SOFCs, and the proposed design of monopolar SOFC blocks allows their usage in developing mobile electrochemical generators both for operable land transport and for unmanned aircraft and underwater vehicles.

Figure 1. Cross-section of a membrane electrode assembly (MEA) of metal-supported SOFC.

Fig.2. Electrochemical characteristics of metal-supported SOFC.

Publications:

1. Erilin, I.S. Aerosol deposition of anode functional layer for metal-supported solid oxide fuel cells / I.S. Erilin, I.N. Burmistrov, D.A. Agarkov, E.A. Agarkova, D.V. Yalovenko, A.A. Solovyev, S.V. Rabotkin, V.E. Pukha, N.V. Lyskov, S.I. Bredikhin // Materials Letters. – 2022. – Vol. 306, Iss. 1. – P. 130924. – DOI:10.1016/j.matlet.2021.130924

2. Russian Patent № 212913 (12.08.2022) "Planar solid oxide fuel cell block with central axis bonding. I.N. Burmistrov, I.S. Erilin, M.N. Levin, S.I. Bredikhin.

Commercial contract №1316-22 with ООО «Innovational Energy Systems» (ООО «ИНЭСИС») ГК «ЭФКО» “OOO INESYS” EFKO Group of Companies

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

9. Surface tension of Cd0.9Zn0.1Te melt

G.V. Kuznetsov, E.B. Borisenko, N.N. Kolesnikov

For the first time, surface tension of the Cd_0.9Zn_0.1Te melt as a function of argon pressure is measured [1].

Stalagmometric method designed for real conditions of AIIBVI crystal growth by vertical zone melting was applied, using a stalagmometer developed at ISSP RAS [2].

It is shown that the obtained dependence, graphically represented in the figure, complies with the Shishkovsky equation

Fig. Dependence of surface tension of Cd_0.9Zn_0.1Te melt on Ar pressure
■ - experimental data, curve - the calculation according to Shyshkovsky equation, taking into account the experimentally determined coefficient values presented in the table.

Table. Coefficients of the Shyshkovsky equation

Using the coefficients of the Shishkovsky equation obtained from the experimental data allowed us to determine the adsorption constant of argon equal to 2.74-10⁶ cm³/mol (assuming that the solution of argon in the melt is perfect).

The results are crucial for growing Cd_0,9Zn_0,1Te crystals that are used in semiconductor ionizing radiation detectors.

Publication: Kuznetsov, G. Surface tension of Cd0.9Zn0.1Te melt / G. Kuznetsov, E. Borisenko, N. Kolesnikov // Materials Letters. – 2022. – Vol. 317. – P. 132093. – DOI:10.1016/j.matlet.2022.132093

State assignment:"Physics and technology of new materials and advanced structures"

10. Preparing a high-temperature material based on silicon carbide and molybdenum silicide

S.L. Shikunov, A.V. Kaledin, V.N. Kurlov

A method for producing a ceramic composite material based on silicon carbide and molybdenum silicide has been developed.

It lies in obtaining multifunctional silicon carbide ceramics [Shikunov S.L., Kurlov V.N., Shikunova I.A. Patent RF № 2573146] based on the interaction of silicon melt with carbon, located in a pre-prepared blank of a certain composition and porosity.

When preparing a composition of carbon powders of various fractions and a coking binder, molybdenum powder is added to the furnace blend.

After mixing and pressing/forming the carbon-metal blank, the molybdenum particles are evenly distributed throughout its volume.

During saturation with silicon melt (silicification), silicon reacts both with the carbon of the blank to form a spatial SiC framework, and with molybdenum particles to form silicide.

The ceramic composite material obtained by this method with a bonded SiC framework and molybdenum silicide integrated into it has increased strength and creep resistance at high temperatures and under heavy loads.

State assignment:"Physics and technology of new materials and advanced structures"

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

11. A new Generation of Heat-Resistant Alloys

M.I. Karpov

The Institute of Solid State Physics of the Russian Academy of Sciences has created a new group of heat-resistant alloys for applications at temperatures above 1200°C.

Structurally, the new materials are natural composites in which molybdenum-based solid solutions play the role of the matrix and refractory carbides are the strengthening phases.

Experimental batches of new materials are produced at the experimental technological base of ISSP RAS.

High-temperature mechanical tests of the new alloys showed their ability to withstand heavy loads at temperatures of 1200° and above for several thousand hours.

State assignment:"Physics and technology of new materials and advanced structures"

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

12. Deformation alloying of structural, electronic and optical components

N.V. Klassen, I.S. Tsebruk, S.A. Vinokurov, N.P. Kobelev, E.L. Kolyvanov

Deformation alloying of solid-state items is fundamentally different from previously known thermo-diffusion, laser and plasma treatment, and ion implantation.

In essence, it means dynamic deformation of the near-surface layer with simultaneous application of an alloying agent to the surface.

The deformation is performed by ball or roller rolling or by sliding a solid indentor.

The advantages of this method are as follows.

1) It does not require special conditions such as elevated temperature, vacuum or special atmosphere. The process can be performed in field conditions, even underwater, should the need for the alloying arise.

2) The alloying rate and depth is hundreds of microns in tens of minutes, which is significantly better than thermo-diffusion or implantation.

3) By selecting the deformation parameters it is possible not only to regulate the depth and speed of alloying, but also to form periodic superstructures, which opens up new possibilities for optics and electronics.

4) Deformation alloying allows introduction of soft polymers to form fundamentally new properties, which is not achievable with other alloying methods.

Figure. Optical microscopy of carbon superstructures deposited by ball-rolling into cesium iodide monocrystal, which is a convenient optically transparent model of crystalline materials. On the left is the introduction of carbon microparticles. On the right is the introduction of carbon nanofoam. The running-in duration is 20 minutes.

State assignment: "Coherent States, Dynamics, and Phase Transformations in Liquids and Solids".

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

13.Interface superconductivity in Dirac semimetals

V.D. Esin, O.O. Shvetsov, A.V. Timonina, N.N. Kolesnikov, E.V. Devyatov

At millikelvin temperatures, using the Andreev reflection study, we show the emergence of superconductivity at the interface between a normal metal (gold) and a topological Dirac semimetal.

The latter was Cd₃As₂ as the most studied Dirac semimetal and the new compound NiTe₂, which has been gaining popularity lately.

Both compounds are not superconducting in bulk under experimental conditions, as is the planar gold lead.

We have demonstrated that the emergence of interface superconductivity is universal and irrespective of the specifics of the realizations of electrode-dirac semimetal contact.

This allows to assert the emergence of surface superconductivity at the normal-metal-dirac-semimetal interface due to the formation of a flat band in the spectrum, which was predicted theoretically.

Since flat-zone formation is closely related to the formation of surface states in Dirac semimetals, we confirm our claim by directly observing the diode effect for the Josephson current, which is related to the momentum shift in the topological surface state inder in-plane magnetic field.

Publication: Esin, V.D. Interface Superconductivity in a Dirac Semimetal NiTe₂/ V.D. Esin, O.O. Shvetsov, A.V. Timonina, N.N. Kolesnikov, E.V. Deviatov // Nanomaterials 2022, 12(23), 4114; https://doi.org/10.3390/nano12234114

RSF grant

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

14. Current-induced control of the polarization state in a polar-metal–based WTe₂/SnSe heterostructure

N.N. Orlova, A.V. Timonina, N.N. Kolesnikov, E.V. Devyatov

We demonstrate polarization state control by electron transport through the interface between thin layers of SnSe and WTe₂, which can be used to create ultrafast switches and new memory elements.

We fabricate SnSe/WTe₂ heterostructure, WTe₂ being a polar metal with ferroelectric polarization perpendicular to WTe2 layers, while SnSe ferroelectric semiconductor is polarized in-plane.

Sharp symmetric drop of differential conductance to zero at some threshold bias voltages is demonstrated, which corresponds with 90° change in ferroelectric polarization curve at the interface in the initially in-plane polarized SnSe layer.

Thus, we demonstrate polarization state control by applying small gate voltages to the structure.

Also, SnSe/WTe₂ heterostructure shows re-entrant transition to the low-conductive structural state at abrupt change of the bias voltage even below the threshold values. This allows ultrafast switching in the structure to be realized.

Publication: Orlova, N.N. Current-induced control of the polarization state in a polar-metal–based heterostructure SnSe/WTe2 / N.N. Orlova, A.V. Timonina, N.N. Kolesnikov, E.V. Deviatov // Europhysics Letters. – 2022. – Vol. 138, Iss. 2. – P. 26002. – DOI:>10.1209/0295-5075/ac63dd

RSF grant

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

15. Sapphire cryoprobe with optical monitoring of tissue freezing

I.N. Dolganova, A.K. Zotov, V.N. Kurlov et al.

A sapphire cryoprobe for superficial cryoablation of biological tissues has been developed that allows estimation of tissue freezing depth.

The monotoring is enabled by optical fibers accommodated inside the rod and connected to the source and the detector, and is based on detecting spatially resolved diffuse reflected intensities of tissue optical response.

Four fiber channels of tissue illumination are used, located at different distances from the detection channel. Experimental approbation performed on a test sample demonstrated the possibility of estimating tissue freezing depth up to 10 mm.

The developed cryoprobe improves the efficiency of cryosurgical treatment because it does not require additional methods and imaging tools to assess the movement of the ice front in the tissue.

Fig. a) Schematic diagram of the sapphire cryoprobe; b) photo of the contact end; c) result of estimating tissue freezing depth of the test sample in comparison with the direct measurement of the layer thickness.

Publication: I.N. Dolganova, A.K. Zotov, L.P. Safonova, P.V. Aleksandrova, I.V. Reshetov, K.I. Zaytsev, V.V. Tuchin, V.N. Kurlov. “Feasibility test of a sapphire cryoprobe with optical monitoring of tissue freezing,” Journal of Biophotonics, accepted November, 22, 2022.

RSF grant №19-79-10212

Physical Sciences, branch 1.3.5 “Optics and laser physics”

16. Solid hydrogen solutions with a symmetric miscibility gap

V.D. Muzalevsky, N.S. Orlov et al.

It is shown that the T-x projection of the miscibility gap in solid interstitial MeH_x solutions will be symmetric and the pressure vs. temperature dependence of the corresponding isomorphic phase transformation will be determined by the reaction Me + (z/2)H₂ = MeH_z with a fixed z value attained at T → 0 K, if the mixing Gibbs energy of the solutions is a symmetric two-well function of the H content with a maximum at z/2.

Reducing the problem of thermodynamic equilibrium between phases of variable composition to the problem with phases of constant composition and the use of literature data for pure metal Me and hydride MeH_z allowed us to establish that it is the symmetry of the miscibility gap (Fig. A) that is a sufficient condition for linearity of the experimental dependences of the standard Gibbs energy ΔG⁰(T) for isomorphic transformation in the Pd-H and Pd-D systems (z = 0.63, Fig. B) and in the Ni-H and Ni-D systems (z = 1) within the whole investigated temperature range up to the critical point (the critical points are shown by asterisks in Fig. B).

Before that, no reason for the linearity of the dependence ΔG⁰(T) for the formation of palladium hydride could not be found for several decades.

Publication: Antonov, V.E. Solid metal-hydrogen solutions with a symmetric miscibility gap / V.E. Antonov, V.D. Muzalevsky, N.S. Orlov // International Journal of Hydrogen Energy. – 2022. – Vol. 47. – P. 15198–15208. – DOI:10.1016/j.ijhydene.2022.03.034

State assignment: "Coherent States, Dynamics, and Phase Transformations in Liquids and Solids".

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

17. Circularly Polarized Laser Emission from an Electrically Pumped Chiral Microcavity

A.A. Maksimov, E.V. Filatov, I.I. Tartakovsky, V.D. Kulakovsky et al.

Engineering chiral optical microcavities is a central concept of modern nano-photonics, allowing full control over the polarization of limited electromagnetic modes.

Here, we demonstrate for the first time a compact source of coherent radiation based on an electrically driven, chiral semiconductor microcavity with electric pumping - Vertical-cavity surface-emitting laser (VCSEL).

The device is composed of an AlAs/(Al,Ga)As microcavity containing multiple GaAs quantum wells in the active region and a chiral photonic crystal slab etched in the upper distributed Bragg reflector (see Fig. 1).

Figure 1

Figure 2

The structure promotes laser oscillation with a narrow spectral and angular emission distribution under electrical current injection in the near-infrared spectral range (ω≃1.565eV) and degrees of circular polarization exceeding 90% in some modes (see Figure 2).

The sense of circular polarization of laser generation is controlled by the handedness of the chiral photonic crystal slab and changes to the opposite one in a mirror-symmetrical structure.

The conventional method of producing circularly polarized emission using quarter-wave slabs made of birefringent materials does not meet the requirements of compactness and compatibility with semiconductor technologies for making nanophotonic elements and circuits.

Our results represent an important step towards practical realization of compact circularly polarized light sources without the application of an external magnetic field or the use of spin-polarized pumping.

Publication: Maksimov, A.A. Circularly Polarized Laser Emission from an Electrically Pumped Chiral Microcavity / A.A. Maksimov, E.V. Filatov, I.I. Tartakovskii, V.D. Kulakovskii, S.G. Tikhodeev, C. Schneider, S. Höfling // Physical Review Applied. – 2022. – Vol. 17, Iss. 2. – P. L021001. – DOI:10.1103/PhysRevApplied.17.L021001

State assignment: "Collective phenomena in electronic and exciton systems in semiconductor nanostructures"

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

18. Transformation of PMMA-SiO₂ core-shell particles into hollow SiO₂ particles

N.S. Sukhinina, V.M. Masalov, T.N. Fursova, I.I. Khodos, I.I. Zverkova, A.A. Zhokhov, G.A. Emelchenko

PMMA-SiO₂ hybrid core-shell particles and hollow SiO₂ particles were synthesized according to a newly introduced method.

It allows to obtain hollow silicon dioxide particles of submicron sizes of a given diameter in the range of 100-1000 nm with an accuracy of 10 nm and a shell thickness of 5-100 nm with an accuracy of ± 2 nm (see Fig. 1).

Electron microscopy, infrared spectroscopy, and X-ray diffraction methods were used to study changes in the morphology and structure of PMMA-SiO₂ core-shell particles during their transformation into hollow SiO₂ particles during heat treatment [1].

The results can be used for engineering of: a white pigment to replace TiO₂ in foods and medicaments, nanocontainers for targeted medicament delivery, new effective catalysts, new composite materials with increased thermal resistance, reduced density and thermal conductivity, to store hydrogen in a molecular form and for solving other urgent problems of materials science.

Figure 1. SEM images of PMMA particles 440 ± 21 nm in size (a) and hybrid PMMA-SiO₂ particles 505 ± 18 nm in diameter obtained from them (б), TEM images of hollow SiO₂ particles (в).

Publication: Sukhinina, N.S. Heat-Mediated Transformation of PMMA-SiO₂ Core-Shell Particles into Hollow SiO₂ Particles / N.S. Sukhinina, V.M. Masalov, T.N. Fursova, I.I. Khodos, I.I. Zverkova, A.A. Zhokhov, G.A. Emelchenko // Crystals. – 2022. – Vol. 12, Iss. 7. – P. 883. – DOI:10.3390/cryst12070883

State assignment "Physics and technology of new materials and structures"

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

19. Peierls Instability of the Lieb Lattice

M.I. Ryzhkin, A.A. Levchenko, I.A. Ryzhkin

It is shown for the first time that a two-dimensional Llieb lattice, or a line-centetred square lattice is unstable with respect to certain correlated displacements of the edge atoms from the lattice sites along the edges. 

The reason lies in the decrease in the electron energy due to such displacements.

At weak instability, the decrease in the electron energy does not exceed the increase in the elastic energy of the ion lattice, which gives rise to anharmonic phonons and soft phonon modes.

In the case of a pronounced instability, when the electron energy decrease does exceed the increase in the elastic energy of the ion lattice, the energy of the edge atoms takes the form of a double-well potential. The quantum tunneling of edge atoms between equilibrium positions results in the formation of quantum tunneling modes. 

The extension of the model under study to the three-dimensional lattices, for example, perovskites and hydrogen-bonded lattices, is considered possible. It can be applied to a broad range of issues, from the problem of high-temperature superconductors and the problem of rapid proton transport, to various physical processes in biological compounds.

Publication: Ryzhkin, M.I. Peierl's instability of the Lieb lattice / M.I. Ryzhkin, A.A. Levchenko, and I.A. Ryzhkin // JETP Letters. - 2022. - vol. 116, № 5. - pp. 300-306. – DOI:10.31857/S1234567822170062 (in Russian)

RSF grant 22-22-00005

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

20. A new thinning mechanism in freely suspended smectic nanofilms

P.V. Dolganov, V.K. Dolganov

A new mechanism of thinning of freely suspended smectic liquid crystals at a temperature above the temperature of the Smectic-A–isotropic liquid bulk phase transition is discovered.

The thinning effect of freely suspended nanofilms was discovered by an American group in 1994 (Stoebe et al., Phys. Rev. Lett., 1994) and was later being actively researched both experimentally and theoretically.

We show that the thinning transition can not only be linked with the film instability, as was considered before, but also with instability in the area where the film is adjacent to the bulk sample (traditionally called a meniscus, as with liquids).

We also show that near the thinning transitions substantial changes in the shape and size of the meniscus can occur (see Fig.1).

Due to instability a thinner region is formed in the meniscus, which can induce the thinning of the whole nanofilm.

Such meniscus instability induced nanofilm thinning differs from that previously described or predicted in experimental and theoretical works.

Fig. 1. Development of instability in the meniscus leading to thinning of the nanofilm.
(a) The smectic film (right part of photo (a)) and its meniscus (left part of photo (a)) far from the thinning temperature.
(b) Heating-induced transformation of the shape of the meniscus near its contact with the smectic film
(c) Formation of a wide flat region in the thinner part of the meniscus
(d) Meniscus with smooth thickness variation (intensity of light reflection decreases when approaching the film).
(e) Formation of a thin region in the meniscus (dark region) leads to the thinning of the film
(f)Meniscus and a thinner film after the thinning transition. The longitudinal size of the meniscus has decreased after the transition. The photos were taken in reflected light.

Publication: Dolganov, P.V. Smectic nanofilms thinning initiated by meniscus / P.V. Dolganov, V.K. Dolganov, E.I. Kats // JETP Letters. - 2022. - Vol. 115, № 4. - pp. 236-240. – DOI:10.31857/S1234567822040061 (in Russian)

State assignment: "Coherent States, Dynamics, and Phase Transformations in Liquids and Solids".

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"

21. Thermal stability of saturated hydrogen solid solutions in silica glass at normal pressure

V.S. Efimchenko, K.P. Meletov

Raman spectroscopy allowed for the first time to examine the thermal stability of saturated solid solutions of molecular hydrogen in silica glass containing 0.58 to 0.7 moles of H₂ per 1 mole of SiO₂ at normal pressure.

At T=143÷190 K, an exponential irreversible decrease in the relative intensity of the rotational modes of the H₂ molecule with annealing time was observed, associated with hydrogen desorption (left panel of Figure 1).

The time constants obtained from these dependencies decrease with increasing temperature, according to the Arrhenius equation τ(T)=A*exp(E_A/k_BT), where τ is the exponential decay time constant, 1/k_BT is the inverse annealing temperature, E_A =(0.16±0.01) eV is activation energy, A=(2.7±0.3)×10^-2 sec is time constant, k_B is Boltzmann constant (right-hand panel of Figure 1).

Using these data, it was determined that the hydrogen content of quartz glass hydrides should halve in 17 years of storage at liquid nitrogen temperature or in 10 seconds at room temperature.

The instability of quartz glass hydrides at room temperature is related to the weak Van der Waals interaction of hydrogen molecules with the silicon and oxygen atoms of quartz glass.

Below is the Raman spectrum of hydrogenated quartz glass at different time intervals. In the upper right corner is the change of the relative intensity of H₂ rotational mode with time. 

Time constants in Arrhenius coordinates.

Publication: Meletov, K.P. Stability of hydrogenated silica glass and desorption kinetics of molecular hydrogen / K.P. Meletov, V.S. Efimchenko // Chemical Physics Letters. – 2022. – Vol. 793. – P. 139477. – DOI:10.1016/j.cplett.2022.139477

State assignment: "Coherent States, Dynamics, and Phase Transformations in Liquids and Solids".

Physical Sciences, branch 1.3.2. "Physics of Condensed Media and Physical Materials Science"