Linear magnetoresistance with a universal energy scale in the strong-coupling superconductor Mo 8 Ga 41 without quantum criticality

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 ${\\mathrm{Mo}}_{8}{\\mathrm{Ga}}_{41}$, a nearly isotropic strong electron-phonon coupling superconductor with a linear-in-temperature resistivity from the transition temperature to $\\ensuremath{\\sim}55$ 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 data sets are remarkably similar to magnetoresistance data of the optimally doped ${\\mathrm{La}}_{2\\ensuremath{-}x}{\\mathrm{Sr}}_{x}{\\mathrm{CuO}}_{4}$, despite the clearly different crystal and electronic structures, and the apparent absence of quantum critical physics in ${\\mathrm{Mo}}_{8}{\\mathrm{Ga}}_{41}$. A new empirical scaling formula is developed, which is able to capture the key features of the low-temperature magnetoresistance data of ${\\mathrm{Mo}}_{8}{\\mathrm{Ga}}_{41}$, as well as the data of ${\\mathrm{La}}_{2\\ensuremath{-}x}{\\mathrm{Sr}}_{x}{\\mathrm{CuO}}_{4}$.