Criticality vs material inhomogeneity: an analysis of LSCO magnetoresistance data

Recent thin-film LSCO measurements have observed, in addition to the hallmark T-linear resistivity of cuprates near optimal doping, B-linear resistivity in strong magnetic fields. We analyze existing data on this thin-film sample to demonstrate that, contrary to the high-Tc iron superconductors near optimal doping, no single scaling function of temperature and field can describe the magnetoresistance data across all measured temperatures above and below the superconducting Tc. We model the high-temperature data within a classically-disordered system of conducting patches with qualitative accuracy. Interestingly, the breakdown of this model at low temperatures when the mean free path exceeds the lengthscale of disorder happens to correspond with the experimentally observed region where the resitivity changes character to become simultaneously T,B linear.

DOI 10.1103/PhysRevB.100.155139