Conductance Change Induced by the Rashba Effect in the LaAlO<SUB>3</SUB>/SrTiO<SUB>3</SUB> Interface

Abstract

The LaAlO3/SrTiO3 (LAO/STO) heterostructure has an inherent space inversion asymmetry causing an internal electric field near the interface. The Rashba spin-orbit coupling arising from this structural characteristic has a considerable influence on spin transport. With application of an external magnetic field, we observed conductance change in the LAO/STO interface which depends on the sign and magnitude of the field. Our systematic study revealed that these results come from spin dependent transport, by which we obtained quantitative strength of the Rashba effect. The Rashba strength in this system depends on the temperature: it varies from 2.6 x 10(-12) eVm to negligible value in the temperature range of 1.8 K-12 K. This method for detecting Rashba effect covers a wider temperature range in comparison with those obtained from Shubnikov-de Haas oscillation or weak antilocalization measurements.

Detection and Control of the Effective Magnetic Field in a Ca‐Doped Bi2Se3 Topological Insulator

“…As shown by the red curve in Figure 3b, the magnetoresistance for the parallel alignment (θ = 0°) is smaller than that for the antiparallel alignment (θ = 180°) between B A and the spin polarization of the surface state, consistent with the results in Figure 2b. This result is very similar to that of a Rashba system such as an asymmetric quantum well [43] or a LaAlO 3 -SrTiO 3 heterostructure, [44,45] implying that the current induces an effective magnetic field with a specific sign. In the same sense, the TI also can be regarded as a kind of Rashba system.…”

“…This unusual phenomenon confirms that the spin-momentum arises in the TI channel and interacts with the applied magnetic field. [43][44][45][46] An intriguing question is what happens when a ferromagnet (FM) layer is brought onto the TI. We investigated the transport property at a TI/FM interface using an 80 nm-thick Ni 81 Fe 19 electrode with lateral dimensions of 0.4 µm × 10 µm, deposited onto the Ca-doped Bi 2 Se 3 topological insulator.…”

“…This unusual phenomenon confirms that the spin‐momentum arises in the TI channel and interacts with the applied magnetic field. [ 43–46 ]…”

“…In a Rashba channel, the magnetoresistance depends not only on the external field but also on the effective Rashba field. [43][44][45][46] The spin-momentum locking phenomenon in TIs can be regarded as the extreme case of Rashba spin splitting, and the AMR is determined by the interaction between the spin-momentum locking and the applied magnetic field. Given the bias current direction, the spin orientation of the TI surface remains constant with respect to a rotating magnetic field.…”