Gate Tunable Spin-Orbit Coupling and Weak Antilocalization Effect in an Epitaxial La₀.₆₇Sr₀.₃₃MnO₃ Thin film
Shao-Pin Chiu1*, Michihiko Yamanouchi2,3, Tatsuro Oyamada3, Hiromichi Ohta2,3, Juhn-Jong Lin1,4
1Institute of Physics, National Chiao Tung University, Hsinchu, Taiwan
2Research Institute for Electronic Science, Hokkaido University, Sapporo, Japan
3Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
4Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
* Presenter:Shao-Pin Chiu,
Epitaxial La₀.₆₇Sr₀.₃₃MnO₃ (LSMO) films have been grown on SrTiO₃ (001) substrates via pulsed laser deposition. In a 22-nm thick LSMO film with a low residual resistivity of ρ₀ ≈ 59 μΩ cm, we found a zero-field dip in the magnetoresistance (MR) below 10 K, manifesting the weak antilocalization (WAL) effect due to strong spin-orbit coupling (SOC). We have analyzed the MR data by including the D’yakonov-Perel’ spin-relaxation mechanism in the WAL theory. We explain that the delocalized spin-down electron subband states play a crucial role for facilitating marked SOC in clean LSMO. Moreover, we find that the SOC strength and gate voltage tunability is similar to that in the 2DEG at LaAlO₃/SrTiO₃ interface, indicating the presence of an internal electric field near the LSMO/SrTiO₃ interface. In a control measurement on a 5-nm thick high resistivity (ρ₀ ≈ 280 μΩ cm) LSMO film, we observe only a small zero-field peak in MR from weak localization effect, indicating negligible SOC.

Keywords: La₀.₆₇Sr₀.₃₃MnO₃, weak antilocalization effect, strong spin-orbit coupling