We report a study of enhancing the magnetic ordering in a model magnetically doped topological insulator (TI), Bi2-xCrxSe3, via the proximity effect using a high-TC ferrimagnetic insulator Y3Fe5O12. The FMI provides the TI with a source of exchange interaction yet without removing the nontrivial surface state. By performing the elemental specific X-ray magnetic circular dichroism (XMCD) measurements, we have unequivocally observed an enhanced TC of 50 K in this magnetically doped TI/FMI heterostructure. We have also found a larger (6.6 nm at 30 K) but faster decreasing (by 80% from 30 K to 50 K) penetration depth compared to that of diluted ferromagnetic semiconductors (DMSs), which could indicate a novel mechanism for the interaction between FMIs and the nontrivial TIs surface.
@article{arxiv.1503.07893,
title = {Enhancing Magnetic Ordering in Cr-doped Bi2Se3 using High-TC Ferrimagnetic Insulator},
author = {Wenqing Liu and Liang He and Yongbing Xu and Koichi Murata and Mehmet C. Onbasli and Murong Lang and Nick J. Maltby and Shunpu Li and Xuefeng Wang and Caroline A. Ross and Peter Bencok and Gerrit van der Laan and Rong Zhang and Kang. L. Wang},
journal= {arXiv preprint arXiv:1503.07893},
year = {2015}
}