Epitaxial La2/3Sr1/3MnO3 (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.
@article{arxiv.1708.02338,
title = {Gate tunable spin-orbit coupling and weak antilocalization effect in an epitaxial La$_{2/3}$Sr$_{1/3}$MnO$_3$ thin film},
author = {Shao-Pin Chiu and Michihiko Yamanouchi and Tatsuro Oyamada and Hiromichi Ohta and Juhn-Jong Lin},
journal= {arXiv preprint arXiv:1708.02338},
year = {2017}
}