Giant electrostatic modification of magnetism via electrolyte-gate-induced cluster percolation in La1−xSrxCoO3−δ
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Electrical control of magnetism is a long-standing goal in science and technology, with the potential to enable a next generation of low-power memory and logic devices. Recently developed electrolyte gating techniques provide a promising route to realization, although the ultimate limits on modulation of magnetic properties remain unknown. Here, guided by a recent theoretical prediction, we demonstrate large enhancement of electrostatic modulation of ferromagnetic order in ion-gel-gated ultrathin films of the perovskite La0.5Sr0.5CoO3−δ by thickness tuning to the brink of percolation. Application of only 3–4 V is then shown capable of inducing a clear percolation transition from a short-range magnetically ordered insulator to a robust long-range ferromagnetic metal with perpendicular magnetic anisotropy. This realizes giant electrostatic Curie temperature modulation over a 150 K window, outstanding values for both complex oxides and electrolyte gating. In operando polarized neutron reflectometry confirms gate-controlled ferromagnetism, additionally demonstrating, surprisingly, that electrostatically induced magnetic order can penetrate substantially deeper than the Thomas-Fermi screening length.
This article is published as Walter, Jeff, T. Charlton, H. Ambaye, M. R. Fitzsimmons, Peter P. Orth, R. M. Fernandes, and Chris Leighton. "Giant electrostatic modification of magnetism via electrolyte-gate-induced cluster percolation in La1−xSrxCoO3−δ." Physical Review Materials 2, no. 11 (2018): 111406. DOI: 10.1103/PhysRevMaterials.2.111406. Posted with permission.