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 The thermodynamic critical field and specific heat of superconducting state in phosphorene under strain

2019 ◽  
Vol 33 (07) ◽  
pp. 1950079
Author(s):  
Kamila A. Szewczyk ◽  
Adam Z. Kaczmarek ◽  
Ewa A. Drzazga
Keyword(s):  
Specific Heat ◽  
Critical Field ◽  
Superconducting State ◽  
Bcs Theory ◽  
High Electron ◽  
Electron Phonon Coupling ◽  
Difference Formula ◽  
Wide Range ◽  
State Formula ◽  
Thermodynamic Critical Field

In this work, we present the thermodynamic properties of the superconducting state in phosphorene. In particular, we have examined the electron doped [Formula: see text] and biaxially strained (4%) monolayer of black phosphorous, which exhibits best thermodynamic stability and highest superconducting critical temperature [Formula: see text] among all monolayer phosphorene structures. Due to the confirmed electron–phonon pairing mechanism and relatively high electron–phonon coupling constant in the studied material, we carried out the calculations in the framework of the Eliashberg formalism for a wide range of the Coulomb pseudopotential [Formula: see text]. We have determined the thermodynamic critical field [Formula: see text], and the specific heat difference [Formula: see text] between superconducting [Formula: see text] and normal state [Formula: see text] as the functions of the temperature. In addition, we have calculated the dimensionless parameters [Formula: see text]/[Formula: see text] and [Formula: see text]/[Formula: see text], and also found their significant deviation from the expectations of the BCS theory. In particular, [Formula: see text] and [Formula: see text] for [Formula: see text].

Anisotropy of upper critical field and surface superconducting state in the intermediate-valence superconductor CeIr3

2020 ◽  
Vol 102 (17) ◽  
Author(s):  
Yoshiki J. Sato ◽  
Fuminori Honda ◽  
Yusei Shimizu ◽  
Ai Nakamura ◽  
Yoshiya Homma ◽  
...  
Keyword(s):  
Critical Field ◽  
Superconducting State ◽  
Upper Critical Field ◽  
Intermediate Valence

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.

Upper critical field of β-(BEDT-TTF)2I3 in the high Tc superconducting state

Physica B+C ◽  
1986 ◽  
Vol 143 (1-3) ◽  
pp. 366-368 ◽  
Author(s):  
Keizo Murata ◽  
Naoki Toyota ◽  
Madoka Tokumoto ◽  
Hiroyuki Anzai ◽  
Gunzi Saito ◽  
...  
Keyword(s):  
Critical Field ◽  
Superconducting State ◽  
Upper Critical Field ◽  
High Tc

INVESTIGATION OF THE SUPERCONDUCTING PHASE IN METALLIC HYDROGEN NEAR THE PRESSURE OF METALLIZATION

2014 ◽  
Vol 28 (02) ◽  
pp. 1450010
Author(s):  
MARCIN W. JAROSIK ◽  
ARTUR P. DURAJSKI
Keyword(s):  
Thermodynamic Properties ◽  
Thermodynamic Parameters ◽  
Superconducting State ◽  
Superconducting Phase ◽  
The Other ◽  
Bcs Theory ◽  
Metallic Hydrogen ◽  
Other Hand ◽  
Eliashberg Formalism ◽  
Coulomb Pseudopotential

In this paper, the thermodynamic properties of the superconducting state in the metallic hydrogen under the pressure at 347 GPa have been determined. In the framework of the Eliashberg formalism, it has been shown that the characteristic thermodynamic parameters deviate from the predictions of the BCS theory. In particular, the ratio ΔC(TC)/CN(TC) decreases from 1.96 to 1.72 depending on the assumed value of the Coulomb pseudopotential (μ* ∈ 〈0.08, 0.15〉). On the other hand, the ratio [Formula: see text] increases from 0.150 to 0.158.

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
Sign in / Sign up

Export Citation Format

Share Document