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.

A room-temperature magnetic semiconductor from a ferromagnetic metallic glass

“…5a. Such method has proven to be effective for realizing stable modulation of carrier densities even when the gate voltage is removed282930. When V G is positive, the holes move along the direction of the electric field and some of them annihiliate once combined with electrons from the Au electrode (Fig.…”

Electrical control of magnetism in oxides

“…[127] The introduction of oxygen vacancies makes the non-volatile and in-depth effect reasonable. [20] For example, the electrically reversible control of ferromagnetic phase transition based on oxygen vacancies migration in manganite film was reported by Cui et al. [20] The formation of an insulating and magnetically hard phase induced by the migration of oxygen in the magnetically soft matrix was directly observed in the further the development of four-state memories, which can be manipulated by a combination of electrode gating and the application of a magnetic field [ Fig.…”

“…[19] The external electric field alters the lattice or shape of the ferroelectric crystal by the converse piezoelectric effect during switching, and then transfer the strain to the proximate magnetic layer, leading to the changes in magnetic anisotropy, magnetization rotation, and coercive through the magnetostriction. Another novel mechanism to be mentioned is the oxygen migration effect or redox reaction effect 4 especially at metal-oxide interface or oxide heterostructures, where the migration of oxygen causes transition of ferromagnetic phase [20] or affects the orbital occupancy and magnetic anisotropy. [21] The electric effect of magnetism is compatible with complementary metal-oxide-semiconductor (CMOS) technology and paves its way towards spintronic-integrated circuits with ultralow power consumption.…”

Electrical Manipulation of Orbital Occupancy and Magnetic Anisotropy in Manganites

“…[25] XPS depth profiling in our previous work. [22] Compared with the electrostatic manipulation based on the capacitance of EDL, [26] the change of x in our system is rather large as the variation of oxygen vacancies is sensitive to the external electric field. We now address the question how the orbital occupancy varies under the electric field.…”