The letter deals with the spin-freezing process observed by means of NMR-NQR relaxation or by muon spin rotation in underdoped cuprate superconductors. This phenomenon, sometimes referred as coexistence of antiferromagnetic and superconducting order parameters, is generally thought to result from randomly distributed magnetic moments related to charge inhomogeneities (possibly stripes) which exhibit slowing down of their fluctuations on cooling below Tc . Instead, we describe the experimental findings as due to fluctuating, vortex-antivortex, orbital currents state coexisting with d-wave superconducting state. A direct explanation of the experimental results, in underdoped Y1−xCaxBa2Cu3O6.1 and La2−xSrCuO4, is thus given in terms of freezing of orbital current fluctuations.
@article{arxiv.cond-mat/0103282,
title = {On the "spin-freezing" mechanism in underdoped superconducting cuprates},
author = {M. Eremin and A. Rigamonti},
journal= {arXiv preprint arXiv:cond-mat/0103282},
year = {2009}
}