Anisotropic bilinear magnetoresistance in (110) SrTiO3 -based two-dimensional electron gas

Bilinear magnetoresistance (BMR), the magnetoresistance that is linear against either magnetic field or applied current, is a hot topic of recent investigations. While most of the previous works focused on isotropic BMR, here we report on a strongly anisotropic BMR for (110) $\mathrm{SrTi}{\mathrm{O}}_{3}$-based two-dimensional electron gas (2DEG). Remarkably, the BMR measured along the [001] axis can be fivefold as large as that obtained along the $[1\overline{1}0]$ axis. A close relation is found between BMR and current-induced effective Rashba field, and it is the anisotropy of the Rashba field that causes the anisotropic BMR. Based on the analysis of anisotropic magnetoresistance, effective Rashba fields up to 4.5 T are determined. The band structure of the 2DEG is further calculated, ellipse-shaped Fermi rings are obtained, and the respective effects of different Fermi rings on BMR are distinguished. This work demonstrates the great potential of anisotropic 2DEG for the exploration of unusual effects.