Disorder Induced BCS–BEC Crossover in an Ultracold Fermi Gas

• Published in: Journal of superconductivity and novel magnetism Vol. 26; no. 5; pp. 1891 - 1895
• Main Authors: Khan, Ayan, Basu, Saurabh, Tanatar, B.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-05-2013; Springer
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Magnetic Materials; Magnetism; Original Paper; Physics; Physics and Astronomy; Quantum fluids and solids; liquid and solid helium; Strongly Correlated Systems; Superconductivity; BCS-BEC crossover; Superconductivity; disorder effects; Random potential; Fluctuations; Fermi gas; Impurities; BEC BCS crossover; Superfluid; Self consistency; Chemical potential; Order parameters
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-012-1949-7

We develop the formalism for BCS–BEC crossover in the presence of weak random impurity and calculate the effect of the random potentials on the basic mean-field quantities. The disorder has been included through the Nozières and Schmitt–Rink theory of superconducting fluctuations, and we obtain the disorder induced superfluid order parameter and chemical potential through a self-consistent calculation. We also calculate the condensate fraction which reveals a distinct nonmonotonic behavior. The downturn in the latter result occurs at the crossover regime with gradual depletion on the BEC side. The non-monotonic feature in the condensate fraction data has been measured in clean systems. Motivated by the above result, we discuss the stability of a disordered fermionic superfluid in the crossover regime.