2002/04/03 by V. A. Ivanov, Ivanov, V. A., J. J. Betouras +3
Physics and Astronomy · #FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con) #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.48550/arxiv.cond-mat/0204085
10 pages, presented at NATO ARW on "Recent trends in the theory of physical phenomena in high magnetic fields", February 2002, Les Houches; Replaced with revised version, misprints corrected
arxiv created 2003/01/24 · arxiv updated 2009/11/30
We present a Ginzburg-Landau theory for a two-band superconductor with emphasis on MgB2. Experiments are proposed which lead to identification of the possible scenarios: whether both σ- and π-bands superconduct or σ% -alone. According to the second scenario a microscopic theory of superconducting MgB2 is proposed based on the strongly interacting % σ-electrons and non-correlated π-electrons of boron ions. The kinematic and Coulomb interactions of σ% -electrons provide the superconducting state with an anisotropic gap of s% *-wave symmetry. The critical temperature Tc has a non-monotonic dependence on the distance r between the centers of gravity of σ- and π-bands. The position of MgB2 on a bell-shaped curve Tc (% r) is identified in the overdoped region. The derived superconducting density of electronic states is in agreement with available experimental and theoretical data. It is argued that the effects of pressure are crucial to identify the microscopic origin of superconductivity in MgB2. Possibilities for Tc increase are discussed.