Analysis of dichroism in the electromagnetic response of superconductors

Abstract

The absorption of polarized light in superconductors is studied within the framework of the Bogolubov-de Gennes approach to inhomogeneous superconductors in magnetic fields. Several mechanisms which give rise to a polarization-dependent absorption ͑i.e., dichroism͒ in superconductors are analyzed in detail. The relation to the absorption of unpolarized light in superconductors and to the absorption of polarized light in normal conductors is investigated and several effects, not known from either of these cases, are found. These effects arise from the interplay of broken chiral symmetry, which produces dichroism, with the superconducting coherence. One potential source for dichroism, namely spin-orbit coupling, is investigated numerically for a simple model superconductor. ͓S0163-1829͑98͒01122-9͔

Relativistic framework for microscopic theories of superconductivity. II. The Pauli equation for superconductors

“…This phenomenon, termed dichroism, is mainly due to SOC. [40][41][42][43] With the exception of dichroism, all these effects were, as yet, analyzed on the basis of the conventional SOC only. In each case the ASOC terms provide an additional source of spin-orbit coupling which has a very different temperature behavior as compared to the conventional SOC.…”

“…In each case the ASOC terms provide an additional source of spin-orbit coupling which has a very different temperature behavior as compared to the conventional SOC. For the case of the absorption of polarized light we have meanwhile investigated the effects of SOC and ASOC in detail [41][42][43] and found that ASOC indeed constitutes an additional, potentially observable, source of dichroism, which is distinguished by its temperature dependence and unique coherence factors.…”

Relativistic framework for microscopic theories of superconductivity. I. The Dirac equation for superconductors

“…It has been noted before by many authors that relativistic effects can have a profound influence on superconductivity. Spin-orbit coupling, a relativistic effect of second order in v/c, is known to influence the symmetry of the order parameter, 1-4 the spin-susceptibility and the Knight shift, 5,6 magnetic impurities in superconductors, 7 Josephson currents, 1,8-10 the value of the upper critical field, 11,12 H c2 , and the magnetooptical response of superconductors, [13][14][15] among other quantities. Relativistic corrections to the Cooper pair mass have been evaluated theoretically and measured experimentally.…”

“…The theory has meanwhile been shown to lead to potentially observable effects on, e.g., the energy spectrum of a superconductor 29 and on the magneto-optical response of superconductors. [13][14][15] The present paper provides a more general approach to relativistic effects in superconductors. It is organized as follows: after this introduction we show, in Sec.…”

Theory of Dichroism in the Electromagnetic Response of Superconductors

“…In what follows we study absorption due to pair breaking only, and neglect scattering from unpaired electrons [4]. For the difference DP in the power absorption, this procedure yields the expression [5],…”