Electrical-current-induced magnetic hysteresis in self-assembled vertically aligned La_{2/3}Sr_{1/3}MnO_3:ZnO-nanopillar composites

Abstract

Magnetoresistive random-access memory (MRAM) is poised to become a next-generation information storage device. Yet, many materials challenges remain unsolved before it can become a widely used memory storage solution. Among them, an urgent need is to identify a material system that is suitable for downscaling and is compatible with low-power logic applications. Self-assembled, vertically-aligned La_{2/3}Sr_{1/3}MnO_3:ZnO nanocomposites, in which La_{2/3}Sr_{1/3}MnO_3 (LSMO) matrix and ZnO nanopillars form an intertwined structure with coincident-site-matched growth occurring between the LSMO and ZnO vertical interfaces, may offer new MRAM applications by combining their superior electric, magnetic (B), and optical properties. In this paper, we show the results of electrical current induced magnetic hysteresis in magneto-resistance measurements in these nano-pillar composites. We observe that when the current level is low, for example, 1 uA, the magneto-resistance displays a linear, negative, non-hysteretic B field dependence. Surprisingly, when a large current is used, I > 10 uA, a hysteretic behavior is observed when the B field is swept in the up and down directions. This hysteresis weakens as the sample temperature is increased. A possible spin-valve mechanism related to this electrical current induced magnetic hysteresis is proposed and discussed.