Ultra-low-power magnetization rotation by orbital selection at a La_0.67Sr_0.33MnO₃/SrTiO₃ interface

Reducing the power consumption for magnetization switching is essential for the realization of energy-saving spin devices. Here, using a magnetic tunnel junction consisting of La_0.67Sr_0.33MnO₃ (LSMO) / SrTiO₃ (STO) / LSMO grown on STO (001), we demonstrate a deterministic and magnetic-field-free 90°-magnetization switching solely by applying an extremely small electric field of 0.05 V/nm on the tunnel barrier and an infinitesimal current density of ~ 10^–2 A/cm², which is ~8 orders of magnitude smaller than that in the present magnetic random access memory. We reveal that this magnetization rotation is induced by a sharp change in the magnetic anisotropy (MA), which occurs at the bias voltage V of ~ ±0.1 V. By measuring the angular dependence of the density of states on the magnetization direction for the same device, we show that the change of MA occurs when the quasi-Fermi level (E_F) moves from e_g to t_2g bands at the LSMO/STO interface with increasing |V| [1]. These findings suggest that highly efficient magnetization control can be realized by designing materials so that the E_F lies close to the band edges of different-symmetry orbitals.
[1] L. D. Anh et al., Sci. Rep. 7, 8715 (2017).