Single-parameter scaling in the magnetoresistance of optimally doped La2-xSrxCuO4

We show that the recent magnetoresistance (MR) data on La2-xSrxCuO4 (LSCO) in strong magnetic fields B [P. Giraldo-Gallo, Science 361, 479 (2018)SCIEAS0036-807510.1126/science.aan3178] obeys single-parameter scaling of the form MR(B,T)=f(μH(T)B), where μH-1(T)∼Tα (1≤α≤2), from T=180 K until T∼20 K, at which point the single-parameter scaling breaks down. The functional form of the MR is distinct from the simple quadratic-to-linear combination of temperature and magnetic field found in the optimally doped iron superconductor BaFe2(As1-xPx)2 [I. M. Hayes, Nat. Phys. 12, 916 (2016)1745-247310.1038/nphys3773]. Further, the low-temperature departure of the MR in LSCO from its high-temperature scaling law leads us to conclude that the MR curve collapse is not the result of quantum critical scaling. We examine the classical two-dimensional (2D) effective medium theory (2DEMT) previously [A. A. Patel, Phys. Rev. X 8, 021049 (2018)2160-330810.1103/PhysRevX.8.021049] used to obtain the quadratic-to-linear resistivity dependence on field and temperature for metals with a T-linear zero-field resistivity. It appears that this scaling form results only for a binary, random distribution of metallic components. More generally, we find a low-temperature, high-field region where the resistivity is simultaneously T and B linear when multiple metallic components are present. Our findings indicate that if mesoscopic disorder is relevant to the magnetoresistance in strange metal materials, the binary-distribution model which seems to be relevant to the iron pnictides is distinct from the more broad-continuous distributions relevant to the cuprates. Using the latter, we examine the applicability of 2DEMT to the MR in LSCO and compare calculated MR curves with the experimental data.