scholarly journals Evidence for the Fulde–Ferrell–Larkin–Ovchinnikov state in bulk NbS2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chang-woo Cho ◽  
Jian Lyu ◽  
Cheuk Yin Ng ◽  
James Jun He ◽  
Kwan To Lo ◽  
...  
Keyword(s):  
Critical Field ◽  
Layer Structure ◽  
Upper Critical Field ◽  
Thermodynamic Quantities ◽  
Transition Metal Dichalcogenide ◽  
Transition Line ◽  
Spin Orbit Coupling ◽  
Ising Spin ◽  
Bulk Single Crystals ◽  
Field Transition

AbstractWe present measurements of the magnetic torque, specific heat and thermal expansion of the bulk transition metal dichalcogenide (TMD) superconductor NbS2 in high magnetic fields, with its layer structure aligned strictly parallel to the field using a piezo rotary positioner. The upper critical field of superconducting TMDs in the 2D form is known to be dramatically enhanced by a special form of Ising spin orbit coupling. This Ising superconductivity is very robust to the Pauli paramagnetic effect and can therefore exist beyond the Pauli limit for superconductivity. We find that superconductivity beyond the Pauli limit still exists in bulk single crystals of NbS2 for a precisely parallel field alignment. However, the comparison of our upper critical field transition line with numerical simulations rather points to the development of a Fulde-Ferrell-Larkin-Ovchinnikov state above the Pauli limit as a cause. This is also consistent with the observation of a magnetic field driven phase transition in the thermodynamic quantities within the superconducting state near the Pauli limit.

scholarly journals Superconductivity beyond Pauli's limit in bulk NbS2: Evidence for the Fulde-Ferrell-Larkin-Ovchinnikov state

2020 ◽  
Author(s):  
Chang-woo Cho ◽  
Jian Lyu ◽  
Cheuk Ng ◽  
James Jun He ◽  
Tarob Abdel-Baset ◽  
...  
Keyword(s):  
Critical Field ◽  
Layer Structure ◽  
Upper Critical Field ◽  
Thermodynamic Quantities ◽  
Transition Metal Dichalcogenide ◽  
Transition Line ◽  
Spin Orbit Coupling ◽  
Ising Spin ◽  
Bulk Single Crystals ◽  
Field Transition

Abstract We present magnetic torque, specific heat and thermal expansion measurements combined with a piezo rotary positioner of the bulk transition metal dichalcogenide (TMD) superconductor NbS2 in high magnetic fields applied strictly parallel to its layer structure. The upper critical field of superconducting TMDs in the 2D form is known to be dramatically enhanced by a special form of Ising spin orbit coupling. This Ising superconductivity is very robust against the Pauli limit for superconductivity. We find that superconductivity beyond the Pauli limit still exists in bulk single crystals of NbS2. However, the comparison of our upper critical field transition line with numerical simulations rather points to the development of a Fulde-Ferrell-Larkin-Ovchinnikov state above the Pauli limit as a cause. This is also consistent with the observation of a magnetic field driven phase transition in the thermodynamic quantities within the superconducting state near the Pauli limit.

scholarly journals Pauli-limit upper critical field of high-temperature superconductor La1.84Sr0.16CuO4

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Daisuke Nakamura ◽  
Tadashi Adachi ◽  
Keisuke Omori ◽  
Yoji Koike ◽  
Shojiro Takeyama
Keyword(s):  
High Temperature ◽  
Critical Field ◽  
High Temperature Superconductor ◽  
Upper Critical Field ◽  
Small Contribution ◽  
Spin Orbit Coupling ◽  
Temperature Dependent ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

AbstractThe upper critical field of a cuprate high-temperature superconductor, La1.84Sr0.16CuO4, was investigated by high-frequency self-resonant contactless electrical conductivity measurements in magnetic fields up to 102 T. An irreversible transition was observed at 85 T (T = 4.2 K), defined as the upper critical field. The temperature-dependent upper critical field was argued on the basis of the Werthamer-Helfand-Hohenberg theory. The Pauli-limiting pair-breaking process with a small contribution of the spin-orbit coupling explained the first-order phase transition exhibiting a hysteresis observed at low temperatures.

scholarly journals Thermodynamic Properties of the Superconducting State in Metallic Hydrogen: Electronic Correlations, Non-conventional Electron-Phonon Couplings and the Anharmonic Effects

2021 ◽  
Author(s):  
M. Kostrzewa ◽  
A. P. Durajski ◽  
J. K. Kalaga ◽  
R. Szczȩśniak
Keyword(s):  
Critical Field ◽  
Superconducting State ◽  
Harmonic Approximation ◽  
Upper Critical Field ◽  
Bcs Theory ◽  
Thermodynamic Quantities ◽  
Metallic Hydrogen ◽  
Electronic Correlations ◽  
Electron Phonon Coupling ◽  
Heat Value

AbstractThermodynamical properties of the superconducting state in metallic hydrogen were determined on the basis of the model of two compressed hydrogen planes. We took into account both the on-site and the inter-site electronic correlations (U and K), as well as the relevant non-conventional electron-phonon coupling functions (gU and gK). We proved, within the Eliashberg formalism, that the maximum value of the critical temperature of transition into the superconducting state is about 200 K for the harmonic approximation, and about 84 K for the Morse anharmonic approximation. Omission of the electronic correlations results in a considerable overstatement of the TC value. On the other hand, the TC value is remarkably understated if the non-conventional interactions are disregarded. Other thermodynamic quantities, such as the order parameter, the jump in the specific heat value, the thermodynamic critical field, and the upper critical field, take the values for which the non-dimensional ratios RΔ, RC, RH and RH2 do not differ substantially from the predictions of the BCS theory.

scholarly journals Отличительные особенности фазовых диаграмм тонких неупорядоченных пленок на основе ВТСП YBa-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-7-x-=/SUB=- во внешних магнитных полях

2019 ◽  
Vol 61 (9) ◽  
pp. 1573
Author(s):  
А.В. Антонов ◽  
А.В. Иконников ◽  
Д.В. Мастеров ◽  
А.Н. Михайлов ◽  
С.В. Морозов ◽  
...  
Keyword(s):  
Critical Field ◽  
Positive Curvature ◽  
Gradual Increase ◽  
Landau Theory ◽  
Upper Critical Field ◽  
Implantation Dose ◽  
Theoretical Interpretation ◽  
Transition Line ◽  
Ginzburg Landau ◽  
Superconducting Correlations

AbstractAn unusual decrease in the slope of the upper critical field near T _ c 0 at a gradual increase in the ion implantation dose has been experimentally observed in narrow bridges formed on the base of thin HTSC YBa_2Cu_3O_7 – _ x films, while an increase in the defect concentration usually leads to an increase in the local slope of the phase transition line H _ c 2( T ). In addition, it has been found that the temperature dependence of the upper critical field has a positive curvature near T _ c 0. A possible theoretical interpretation of the results is proposed. It is based on the modified Ginzburg–Landau theory with a nonuniform length of superconducting correlations.

Enhancement of critical temperature and upper critical field due to Nb substitution in Zr-V alloy superconductors

2020 ◽  
Author(s):  
Sabyasachi Paul ◽  
S. K. Ramjan ◽  
L. S. Sharath Chandra ◽  
Archna Sagdeo ◽  
M. K. Chattopadhyay
Keyword(s):  
Critical Temperature ◽  
Critical Field ◽  
Upper Critical Field

scholarly journals Experimental and theoretical analysis of the upper critical field in ferromagnet–superconductor–ferromagnet trilayers

2013 ◽  
Vol 26 (8) ◽  
pp. 085003 ◽  
Author(s):  
E Antropov ◽  
M S Kalenkov ◽  
J Kehrle ◽  
V I Zdravkov ◽  
R Morari ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Critical Field ◽  
Upper Critical Field
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