“Exotic phenomena at oxide LaAlO3/SrTiO3 hetero-interface and their applications”

Dr. Jonghyun Song
Department of Physics, Chungnam National University
Nov. 04 (Fri), 13:30 PM
E6-2. 1st fl. #1323

Abstract: great attentions. Here we report the fabrication of spintronics devices based upon the interface ferromagnetism of LaAlO3/SrTiO3 (LAO/STO) heterostructures. The choice of the LAO/STO structure was inspired by its high-mobility two-dimensional electron gas and a number of experimental investigations revealing the spin ordering at this oxide interface. However, the possibility and mechanisms of this interfacial magnetism are still debated and the spin degree of freedom has not yet been employed adequately. The spin injection in the device in this study is enabled by an appropriately thin epitaxial Ti interlayer. Tunnelling magnetoresistance (TMR) is observed and shows such a strong in-plane anisotropy that the sign changes with the direction of applied magnetic field. This may be due to the strong Rashba-type spin-orbit coupling and the tetragonal domain configuration in the LAO/STO heterointerface. These new findings provide evidence of the interface ferromagnetism of the LAO/STO system, open up possible applications of the spin degree of freedom in the oxide heterointerfaces, and give insight into the interfacial ferromagnetic properties of complex oxide-heterostructures. Our polarity-tunable MTJs pave the way for oxide-based spintronics, in which the spin transport plays a crucial role. Furthermore, we also anticipate that these results may stimulate pursuit of two-dimensional ferromagnetism at oxide interfaces.

1. Thach D.N. Ngo, Jung-Won Chang, Kyujoon Lee, Seungju Han, Joon Sung Lee, Young Heon Kim, Myung-Hwa Jung, Yong-Joo Doh, Mahn-Soo Choi, Jonghyun Song, and Jinhee Kim, ‘Polarity-tunable magnetic tunnel junctions based on ferromagnetism at oxide heterointerfaces’, Nature Communications, 6, 8035(2015).