Reversible Ferromagnetic Phase Transition in Electrode‐Gated Manganites

Abstract

We investigated the dependence of T C and magnetoresistance (MR) on gate voltages ( V G ) in the 20-nm-thick high-quality La 0.6 Sr 0.4 MnO 3 (LSMO) Hall bar gated by ionic liquid (more Reversible Ferromagnetic Phase Transition in ElectrodeGated ManganitesBin Cui , Cheng Song , * Guangyue Wang , Yinuo Yan , Jingjing Peng , Jinghui Miao , Haijun Mao , Fan Li , Chao Chen , Fei Zeng , and Feng Pan * The electronic phase transition has been considered as a dominant factor in the phenomena of colossal magnetoresistance, metal-insulator transition, and exchange bias in correlated electron systems. However, the effective manipulation of the electronic phase transition has remained a challenging issue. Here, the reversible control of ferromagnetic phase transition in manganite fi lms through ionic liquid gating is reported. Under different gate voltages, the formation and annihilation of an insulating and magnetically hard phase in the magnetically soft matrix, which randomly nucleates and grows across the fi lm instead of initiating at the surface and spreading to the bottom, is directly observed. This discovery provides a conceptually novel vision for the electric-fi eld tuning of phase transition in correlated oxides. In addition to its fundamental signifi cance, the realization of a reversible metalinsulator transition in colossal magnetoresistance materials will also further the development of four-state memories, which can be manipulated by a combination of electrode gating and the application of a magnetic fi eld.

Electric-Field Control of Oxygen Vacancies and Magnetic Phase Transition in a Cobaltite/Manganite Bilayer

“…The uniformed gating effect along the depth of the thin film also confirms the comparability of samples with different thicknesses (Fig. S8 of [29] and a previous report [21]). The peak positions of Co-(left axis) and Mn-L 3 (right axis) are summarized in Fig.…”

Ionic Liquid Gating Control of Spin Wave Resonance in La0.7Sr0.3MnO3 Thin Film

“…The gating behavior was consistent with the electrochemical window test results and the previous report of the ILG control LSMO magnetic property . Unlike the previous work, the oxygen vacancies was accumulated at the film LSMO surface, which might be caused by the gating device difference or the different composition of the LSMO (La 0.6 Sr 0.4 MnO 3 in the previous report) …”

“…For the normal plane direction, the 5 V ILG caused a −92 Oe FMR shift. After the sequential voltage gating, the in‐plane and the out‐plane FMR field shift remained at 63.5 and −63.5 Oe, corresponding to the SWR control results and the previous reports . The reversibility could be improved significantly by decreasing the operating temperature and the gating voltage.…”

Tuning ferromagnetism at room temperature by visible light

“…Indeed, the resistivity of the LSMO film drops upon 4.66 mW•cm −2 white light illumination. This change in resistivity is comparable to the effect of about 0.2-V gating of similar LSMO films (9). This gating level is in perfect agreement with the expected modification in the band structure.…”