ABSTRACT
Electronic structures of rare-earth (R)-doped (
;
) single crystals, which are promising candidates for magnetic topological insulators, have been investigated by employing soft X-ray absorption spectroscopy (XAS), soft X-ray magnetic circular dichroism (XMCD), and circular dichroism (CD) angle-resolved photoemission spectroscopy (ARPES). R
XAS and XMCD measurements provide evidence that R ions are trivalent and magnetic, confirming that doped R ions have purely magnetic effects. ARPES measurements of
show a finite energy gap for x>0, arising from the broken time-reversal symmetry due to magnetic R impurities. CD-ARPES measurements of
reveal finite CD effects in the topological surface states. This work demonstrates that
(
) are magnetic topological insulators.
Acknowledgments
J.-S. Kang congratulates the 80th birthday of Prof. M. Brian Maple, and appreciates very much his prominent contribution to the research on the strongly-correlated electron systems.
Disclosure statement
No potential conflict of interest was reported by the authors.
ORCID
J.-S. Kang http://orcid.org/0000-0002-3012-7673