Dirac quasiparticles and spin-lattice relaxation in the mixed state

TL;DR

This paper uses quantum-mechanical calculations to analyze spin-lattice relaxation in high-Tc cuprate superconductors, revealing non-monotonic behaviors that challenge previous semiclassical interpretations and the role of antiferromagnetic fluctuations.

Contribution

It introduces a quantum-mechanical approach using the Franz-Tesanovic gauge transformation to study spin relaxation, providing new insights into the excitations in the mixed state of high-Tc superconductors.

Findings

Non-monotonic temperature and frequency dependence of relaxation rates

Results differ from semiclassical Doppler-shifted models

Challenges the role of antiferromagnetic fluctuations as primary excitations

Abstract

We present the results of quantum-mechanical calculations, using the singular gauge transformation of Franz and Tesanovic, of the rate of planar Cu spin-lattice relaxation due to electron spin-flip scattering in the mixed state of high-Tc cuprate superconductors. The results show a non-monotonic temperature and frequency dependence that differs markedly from semiclassical Doppler-shifted results and challenges the assertion that recent experimental observations of the rate of planar Cu and O spin-lattice relaxation in the mixed state of YBCO point to antiferromagnetic spin fluctuations as a better candidate for the elementary excitations of the superconducting state.