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Your search keyword '"Chareev, Dmitry A."' showing total 17 results
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17 results on '"Chareev, Dmitry A."'

2. Crystal growth, transport phenomena and two gap superconductivity in the mixed alkali metal $(K_{1-z}Na_z)_{x}Fe_{2-y}Se_2$ iron selenide

Author

Roslova, Maria, Kuzmichev, Svetoslav, Kuzmicheva, Tatiana, Ovchenkov, Yevgeny, Liu, Min, Morozov, Igor, Boltalin, Aleksandr, Shevelkov, Andrey, Chareev, Dmitry, and Vasiliev, Alexander

Subjects
Condensed Matter - Superconductivity
Abstract

Using the self-flux technique we grew superconducting $(K_{1-z}Na_z)_{x}Fe_{2-y}Se_2$ (z = 0.3) single crystals. The EDX mapping revealed the uniform elements distribution on the crystal surface while the XRD measurements indicate that the crystals are compositionally inhomogenous on nanoscale. The physical properties of the as-prepared sample are characterized by electrical resistivity, magnetization and specific heat measurements. Resistivity measurements show the onset of the superconducting transition at 33 K and zero resistivity at 31.7 K. The large upper critical field $H_{c2}$(0) was estimated as high as about of 140 T for the in-plane field and 38 T for the out-of-plane field. The anisotropy of $H_{c2}^{ab}(0)/H_{c2}^{c}(0)$ and coherence lengths $\xi^{ab}(0)/\xi^{c}$(0) was found to be around 3.7. The pioneer studies by multiple Andreev reflections effect spectroscopy ("break-junction" technique) revealed the presence of two anisotropic superconducting gaps $\Delta_L\,=\,(9.3\pm1.5)\,meV$, $\Delta_S\,=\,(1.9\pm0.4)\,meV$, and provided measuring of the $\Delta_L$(T) temperature dependence. The BCS-ratio for the large gap $2\Delta_L/k_BT_c^{bulk}\,\approx\,6.3$ points to a strong electron-boson coupling in the "driving" condensate characterized by $\Delta_L$ order parameter., Comment: 27 pages, 11 figures

Published
2013

3. Interplay between lattice and spin states degree of freedom in the FeSe superconductor: dynamic spin state instabilities

Author

Gnezdilov, Vladimir, Pashkevich, Yurii G., Lemmens, Peter, Wulferding, Dirk, Shevtsova, Tatiana, Gusev, Alexander, Chareev, Dmitry, and Vasiliev, Alexander

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract

Polarized Raman-scattering spectra of superconducting, single-crystalline FeSe evidence pronounced phonon anomalies with temperature reduction. A large 6.5% hardening of the B_1g(Fe) phonon mode is attributed to the suppression of local fluctuations of the iron spin state with the gradual decrease of the iron paramagnetic moment. The ab-initio lattice dynamic calculations support this conclusion. The enhancement of the low-frequency spectral weight above the structural phase transition temperature T_s and its change below T_s is discussed in relation with the opening of an energy gap between low (S=0) and higher spin states which prevents magnetic order in FeSe. The very narrow phonon line widths compared to observations in FeTe suggests the absence of intermediate spin states in the fluctuating spin state manifold in FeSe., Comment: 9 pages, 5 figures

Published
2013
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9. Short-Range and Long-Range Order in AFM–FM Exchange Coupled Compound LiCu2(VO4)(OH)2

Author

Koshelev, Anatoly, primary, Zvereva, Elena, additional, Shvanskaya, Larisa, additional, Volkova, Olga, additional, Abdel-Hafiez, Mahmoud, additional, Gippius, Andrey, additional, Zhurenko, Sergey, additional, Tkachev, Alexey, additional, Chareev, Dmitry, additional, Büttgen, Norbert, additional, Schaedler, Martina, additional, Iqbal, Asif, additional, Rahaman, Badiur, additional, Saha-Dasgupta, Tanusri, additional, and Vasiliev, Alexander, additional

Published
2019
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11. Spin-Order-Induced Ferroelectricity and Magnetoelectric Effect in LiCuFe2(VO4)3

Author

Koshelev, Anatoly V., primary, Zakharov, Konstantin V., additional, Pyatakov, Alexander P., additional, Shvanskaya, Larisa V., additional, Shakin, Alexander A., additional, Volkova, Olga S., additional, Chareev, Dmitry A., additional, Kamusella, Sirko, additional, Klauss, Hans-Henning, additional, Molla, Kaimujjaman, additional, Rahaman, Badiur, additional, Saha-Dasgupta, Tanusri, additional, and Vasiliev, Alexander N., additional

Published
2018
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17. Crystal growth, transport phenomena and two-gap superconductivity in the mixed alkali metal (K1-zNaz)xFe2-ySe2 iron selenide.

Author

Roslova, Maria, Kuzmichev, Svetoslav, Kuzmicheva, Tatiana, Ovchenkov, Yevgeny, Min Liu, Morozov, Igor, Boltalin, Aleksandr, Shevelkov, Andrey, Chareev, Dmitry, and Vasiliev, Alexander

Subjects
SUPERCONDUCTING composites, CRYSTAL structure research, MAGNETIZATION, BOSONS, ELECTROMAGENTIC hypersensitivity
Abstract

Using the self-flux technique we grew superconducting (K1-zNaz)xFe2-ySe2 (z = 0.3) single crystals. EDX mapping revealed the uniform elements distribution on the crystal surface while XRD measurements indicate that the crystals are compositionally inhomogeneous on the nanoscale. The physical properties of the as-prepared sample are characterized by electrical resistivity, magnetization and specific heat measurements. Resistivity measurements show the onset of the superconducting transition at 33 K and zero resistivity at 31.7 K. The large upper critical field Hc2(0) was estimated as high as about 140 T for the in-plane field and 38 T for the out-of-plane field. The anisotropy of Hc2ab (0)/Hc2ab(0) and coherence lengths ξab(0)/ξc(0) was found to be around 3.7. The pioneering studies by multiple Andreev reflections effect spectroscopy ("break-junction" technique) revealed the presence of two anisotropic superconducting gaps ΔL = (9.3 ± 1.5) meV, ΔS = (1.9 ± 0.4) meV, and provided a measurement of the ΔL(T) temperature dependence. The Bardeen-Cooper-Schrieffer (BCS) theory ratio ratio for the large gap 2ΔL/kBTcbulk ≈ 6.3 points to a strong electron-boson coupling in the "driving" condensate characterized by the ΔL order parameter. [ABSTRACT FROM AUTHOR]

Published
2014
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