Kejun (Ben) Xu
Stanford University
ABSTRACT
Since the proposal of a correlation-driven topological state in the prototypical Kondo insulator SmB6, there has been several surprising discoveries [1] such as robust surface transport and quantum oscillations in the insulating state. However, ongoing research efforts are hampered by the lack of suitable material families, comprising of only SmB6 and YbB12 thus far. We propose and study a new class of candidate topological Kondo insulators based on 3d electrons. We focus on FeSb2, a correlated insulator that also displays a ubiquitous low temperature resistivity plateau. Our angle-resolved photoemission spectroscopy results [2] reveal a rich assemblage of metallic 2-dimensional surface states as well as anisotropic flat spectral intensities. Comparison with theoretical calculation show band renormalizations attributable to correlation effects. These findings open a new door to search for correlation-driven physics in these unconventional insulators. Juxtaposition of the 3d Kondo insulators with the 4f compounds will allow identification of key ingredients that are responsible for the exotic phenomena.
references
[1] L. Li, K. Sun, C. Kurdak and J. W. Allen. Emergent mystery in the Kondo insulator samarium hexaboride. Nat. Rev. Phys. 2, 463-479 (2020).
[2] K.-J. Xu et al. Metallic surface states in a correlated d-electron topological Kondo insulator candidate FeSb2, Proc. Natl. Acad. Sci. 117 (27) 15409 (2020).
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