Browsing by Subject "Disorder effects"

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    Disorder Induced BCS-BEC Crossover in an Ultracold Fermi Gas
    (Springer, 2013-05) Khan, A.; Basu, S.; Tanatar, Bilal
    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 Nozieres 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.
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    Ground-state energy and compressibility of a disordered two-dimensional electron gas
    (World Scientific Publishing, 2007) Tanatar, Bilal; Subaşı, Ahmet Levent; Esfarjani, K.; Fazeli, S. M.
    Two-dimensional (2D) electron systems in the presence of disorder are of interest in connection with the observed metal-insulator transition in such systems. We use density functional theory in its local-spin density approximation (LSDA) to calculate the ground-state energy of a 2D electron system in the presence of remote charged impurities which up on averaging provides disorder. The inverse compressibility calculated from the ground-state energy exhibits a minimum at a critical density controlled by the disorder strength. Our findings are in agreement with experimental results.