Linear magnetoresistance with a universal energy scale in a strong-coupling superconductor

Abstract

The recent discovery of a nonsaturating linear magnetoresistance in several correlated electron systems near a quantum critical point has revealed an interesting interplay between the linear magnetoresistance and the zero-field linear-in-temperature resistivity. These studies suggest a possible role of quantum criticality on the observed linear magnetoresistance. Here, we report our discovery of a nonsaturating, linear magnetoresistance in Mo8Ga41, a nearly isotropic strong electron-phonon coupling superconductor with a linear-in-temperature resistivity from the transition temperature to ∼55 K. The growth of the resistivity in field is comparable to that in temperature, provided that both quantities are measured in the energy unit. Our datasets are remarkably similar to magnetoresistance data of the optimally doped La2−xSrxCuO4, despite the clearly different crystal and electronic structures, and the apparent absence of quantum critical physics in Mo8Ga41. A new empirical scaling formula is developed, which is able to capture the key features of the low-temperature magnetoresistance data of Mo8Ga41, as well as the data of La2−xSrxCuO4.Recently, interesting cases of nonsaturating linear magnetoresistance (LMR) has been reported in several correlated electron systems, including CrAs under pressure, Ba(Fe 1/3 Co 1/3 Ni 1/3 ) 2 As 2 , La 2−x Ce x CuO 4 , La 2−x Sr x CuO 4 , BaFe 2 (As 1−x P x ) 2 and FeSe 1−x S x (with appropriate x for the latter four) [1][2][3][4][5][6]. In these systems, all related to families of topical superconductors, an intriguing interplay between the thermal and field energy scales have been established. A field-to-temperature scaling which involves a quadrature sum of the thermal and field energy scales, developed by Hayes et al. [5] has been successfully applied to CrAs, BaFe 2 (As 1−x P x ) 2 , FeSe 1−x S x and Ba(Fe 1/3 Co 1/3 Ni 1/3 ) 2 As 2 [1,2,5,6]. However, in the hole-doped cuprate La 2−x Sr x CuO 4 , the resistivity data do not follow the quadrature scaling [4,7], while in the electron-doped cuprate La 2−x Ce x CuO 4 (x=0.175), the resistivity data have been found to be proportional to the direct sum of thermal and field energies [3]. To further understand the interplay between the magnetic field and the temperature, more examples of correlated electron systems showing LMR are needed.