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The electric field effect on ferromagnetism offers a new dimension in the recent advancement of spintronics. We report on the gate control of transport properties in thin films of oxide-based ferromagnetic metal, SrRuO3. An electric double layer transistor configuration was utilized with an ionic liquid dielectric to apply a strong electric field on a SrRuO3 thin film of 5 monolayers in thickness. The application of gate voltage induced a clear electroresistance effect, despite a considerably-large initial carrier density of the order of 1022cm-3. Furthermore, we found that the gate modulation of the anomalous Hall conductivity rx y, which was as large as ~±40% at low temperatures, was about three times larger than that of the longitudinal conductivity σxx. The variation of σxy is characterized by the power-law scaling relation with σx x, which is widely observed in a bad metal regime of the charge transport. [ABSTRACT FROM AUTHOR]

The electric field effect on ferromagnetism offers a new dimension in the recent advancement of spintronics. We report on the gate control of transport properties in thin films of oxide-based ferromagnetic metal, SrRuO3. An electric double layer transistor configuration was utilized with an ionic liquid dielectric to apply a strong electric field on a SrRuO3 thin film of 5 monolayers in thickness. The application of gate voltage induced a clear electroresistance effect, despite a considerably-large initial carrier density of the order of 1022cm-3. Furthermore, we found that the gate modulation of the anomalous Hall conductivity rx y, which was as large as ~±40% at low temperatures, was about three times larger than that of the longitudinal conductivity σxx. The variation of σxy is characterized by the power-law scaling relation with σx x, which is widely observed in a bad metal regime of the charge transport. [ABSTRACT FROM AUTHOR]

Pt is often considered to be an exchange-enhanced paramagnetic material, in which the Stoner criterion for ferromagnetism is nearly satisfied and, thus, external stimuli may induce unconventional magnetic characteristics. We report that a nonmagnetic perturbation in the form of a gate voltage applied via an ionic liquid induces an anomalous Hall effect (AHE) in Pt thin films, which resembles the AHE induced by the contact to Bi-doped yttrium iron garnet. Analysis of detailed temperature and magnetic field experiments indicates that the evolution of the AHE with temperature can be explained in terms of large local moments; the applied electric field induces magnetic moments as large as ~10μB that follow the Langevin function. [ABSTRACT FROM AUTHOR]

The instability of the quantum anomalous Hall (QAH) effect has been studied as a function of the electric current and temperature in ferromagnetic topological insulator thin films. We find that a characteristic current for the breakdown of the QAH effect is roughly proportional to the Hall-bar width, indicating that the Hall electric field is relevant to the breakdown. We also find that electron transport is dominated by variable range hopping (VRH) at low temperatures. Combining the current and temperature dependences of the conductivity in the VRH regime, the localization length of the QAH state is evaluated to be about 5μm. The long localization length suggests a marginally insulating nature of the QAH state due to a large number of in-gap states. [ABSTRACT FROM AUTHOR]