Resistivity minimum in diluted metallic magnets

Abstract

Resistivity minima are commonly seen in itinerant magnets and they are often attributed to the Kondo effect. However, recent experiments are revealing an increasing number of materials showing resistivity minima in the absence of indications of Kondo singlet formation. In a previous work [Z. Wang, K. Barros, G.-W. Chern, D. L. Maslov, and C. D. Batista, Phys. Rev. Lett. 117, 206601 (2016)], we demonstrated that the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction can produce a classical spin liquid state at finite temperature, whose resistivity increases with decreasing temperature. The classical spin liquid exists over a relatively large temperature window because of the frustrated nature of the RKKY interaction produced by a 2D electron gas. In this work, we investigate the robustness of the RKKY-induced resistivity upturn against site dilution, which provides an alternative, and more robust, way of stabilizing the classical spin liquid state down to $T=0$. By using series expansions and stochastic Landau-Lifshitz dynamics simulation, we show that site dilution competes with thermal fluctuations and further stabilizes the resistivity upturn, which is accompanied by a negative magnetoresistivity due to suppression of the electron-spin scattering.