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The superfluid density is a fundamental quantity describing the response to a rotation as well as in two-fluid collisional hydrodynamics. We present extensive calculations of the superfluid density \rho_s in the BCS-BEC crossover regime of…

Materials Science · Physics 2012-05-10 N. Fukushima , Y. Ohashi , E. Taylor , A. Griffin

The pairing and superfluid phenomena in a two-component Fermi gas can be strongly affected by the population and mass imbalances. Here we present phase diagrams of atomic Fermi gases as they undergo BCS--Bose-Einstein condensation (BEC)…

Quantum Gases · Physics 2014-04-24 Jibiao Wang , Hao Guo , Qijin Chen

We study the disorder effects upon superconducting transition temperature T_c and the number of local pairs in attractive Hubbard model within the combined Nozieres - Schmitt-Rink and DMFT+\Sigma approximations. We analyze the wide range of…

Superconductivity · Physics 2018-10-12 E. Z. Kuchinskii , N. A. Kuleeva , M. V. Sadovskii

We theoretically investigate strong-coupling effects on specific heat at constant volume $C_{\rm V}$ in a superfluid Fermi gas with a tunable interaction associated with Feshbach resonance. Including fluctuations of the superfluid order…

Quantum Gases · Physics 2019-05-22 Daisuke Inotani , Pieter van Wyk , Yoji Ohashi

We investigate the crystal structure, transport properties and specific heat in five selected FeSe single crystals containing different amounts of disorder. Transport measurements show that disorder significantly suppresses superconducting…

Superconductivity · Physics 2025-09-15 Jianping Fu , Yue Sun , Jingting Chen , Zhixiang Shi , Tsuyoshi Tamegai

The BCS-to-BEC crossover, as well as the nature of Cooper pairs, in a superconducting and Fermi superfluid medium is studied from the exact ground state wavefunction of the reduced BCS Hamiltonian. As the strength of the interaction…

Superconductivity · Physics 2009-11-11 Gerardo Ortiz , Jorge Dukelsky

We study the time evolution of a system of fermions with pairing interactions at a finite temperature. The dynamics is triggered by an abrupt increase of the BCS coupling constant. We show that if initially the fermions are in a normal…

Superconductivity · Physics 2021-07-20 Emil A. Yuzbashyan , Oleksandr Tsyplyatyev

We investigate strong-coupling effects on normal state properties of an ultracold Fermi gas. Within the framework of $T$-matrix approximation in terms of pairing fluctuations, we calculate the single-particle density of states (DOS), as…

Quantum Gases · Physics 2013-05-29 Shunji Tsuchiya , Ryota Watanabe , Yoji Ohashi

We study the effect of critical pairing fluctuations on the electronic properties in the normal state of a clean superconductor in three dimensions. Using a functional renormalization group approach to take the non-Gaussian nature of…

Superconductivity · Physics 2017-08-08 Philipp Lange , Oleksandr Tsyplyatyev , Peter Kopietz

A superfluid-insulator transition is known to occur in strongly disordered Fermi gases, in both the BCS and BEC regimes; here, we address the properties of this transition across the BEC-BCS crossover. We argue that the critical disorder…

Quantum Gases · Physics 2012-12-05 Sarang Gopalakrishnan

We investigate pairing fluctuation effects in a two band fermionic system, where a shallow band in the Bardeen--Cooper--Schrieffer--Bose--Einstein condensation (BCS-BEC) crossover regime is coupled with a weakly interacting deep band.…

Superconductivity · Physics 2020-01-23 Hiroyuki Tajima , Andrea Perali , Pierbiagio Pieri

A general analysis on Fermion pairing at finite temperature and density between different species with mismatched Fermi surfaces is presented. Very different from the temperature effect of BCS phase, the recently found breached pairing…

Condensed Matter · Physics 2009-11-10 Jinfeng Liao , Pengfei Zhuang

We study s-wave pairing of population imbalanced Fermi atoms in quasi two dimensions using a mean field theory. At zero temperature, we map out the phase diagram in the entire Bardeen, Cooper and Schrieffer-Bose Einstein condensation…

Other Condensed Matter · Physics 2009-08-03 Theja N. De Silva

We consider inter- and intra-species pairing interactions in an asymmetrical Fermi system. Using equation of motion method, we obtain coupled mean-field equations for superfluid gap functions and population densities. We construct a phase…

Superconductivity · Physics 2014-04-24 Renyuan Liao , Khandker F. Quader

We derive a phase diagram for the pseudogap onset temperature $T^*$ (associated with the breakdown of the Fermi liquid state, due to strong pairing correlations) and the superconducting instability, $T_c$, as a function of variable pairing…

Superconductivity · Physics 2007-05-23 Jiri Maly , Boldizsar Janko , K. Levin

We consider the linear BCS equation, determining the BCS critical temperature, in the presence of a boundary, where Dirichlet boundary conditions are imposed. In the one-dimensional case with point interactions, we prove that the critical…

Mathematical Physics · Physics 2024-03-27 Christian Hainzl , Barbara Roos , Robert Seiringer

This article is written as a Lecture given in the 2006 Varenna Summer School on "Ultracold Fermi Gases". Here we present a review of BCS--Bose Einstein condensation (BEC) crossover theory with emphasis on finite temperature effects. We…

Strongly Correlated Electrons · Physics 2011-09-13 K. Levin , Qijin Chen

We investigate unconventional superfluidity in a gas of Fermi atoms with an anisotropic p-wave Feshbach resonance. Including the p-wave Feshbach resonance as well as the associated three kinds of quasi-molecules with finite orbital angular…

Other Condensed Matter · Physics 2009-11-10 Yoji Ohashi

We establish universal behavior in temperature dependencies of some observables in $(s+id)$-wave BCS superconductivity in the presence of a weak $s$ wave. There also could appear a second second-order phase transition. As temperature is…

Strongly Correlated Electrons · Physics 2009-10-31 Angsula Ghosh , Sadhan K. Adhikari

The Cooper-pair size (i.e., the BCS coherence length) in low-dimensional superconductors is dramatically modified by quantum-size effects. In particular, for nanowires made of conventional superconducting materials, we show that the…

Superconductivity · Physics 2009-10-14 A. A. Shanenko , M. D. Croitoru , A. Vagov , F. M. Peeters