Role of the Fermi-Surface Anisotropy in Angle-Dependent Magnetic-Field Oscillations for Identifying the Energy-Gap Anisotropy of AyFe2Se2 Superconductors

Tanmoy Das, Anton B. Vorontsov, Ilya Vekhter, and Matthias J. Graf
Phys. Rev. Lett. 109, 187006 – Published 2 November 2012
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Abstract

We present a numerical study of the field-angle resolved oscillations of the thermal conductivity and specific heat under a rotated magnetic field in the AyFe2xSe2 [A=K, Rb, Cs, (Tl, K)] superconductors, using realistic two-band Fermi surface parametrization. Our key finding is that even for isotropic pairing on an anisotropic Fermi surface, the thermodynamic quantities exhibit substantial oscillatory behavior in the superconducting state, even much below the upper critical field. Furthermore, in multiband systems the competition of anisotropies between two Fermi surfaces can cause a double sign reversal of oscillations as a function of temperature, irrespective of gap anisotropy. Our findings put severe constraints on simple interpretations of field-angle resolved measurements widely used to identify the angular structure of the superconducting gap.

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  • Received 15 March 2012

DOI:https://doi.org/10.1103/PhysRevLett.109.187006

© 2012 American Physical Society

Authors & Affiliations

Tanmoy Das1, Anton B. Vorontsov2, Ilya Vekhter3, and Matthias J. Graf1

  • 1Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
  • 2Department of Physics, Montana State University, Bozeman, Montana 59717, USA
  • 3Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, USA

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Issue

Vol. 109, Iss. 18 — 2 November 2012

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