Abstract
The pristine graphene described with massless Dirac fermion could bear topological insulator state and ferromagnetism via the band structure engineering with various adatoms and proximity effects from heterostructures. In particular, topological Anderson insulator state was theoretically predicted in tight-binding honeycomb lattice with Anderson disorder term. Here, we introduced physi-absorbed Fe-clusters/adatoms on graphene to impose exchange interaction and random lattice disorder, and we observed Anderson insulator state accompanying with Kondo effect and field-induced conducting state upon applying the magnetic field at around a charge neutral point. Furthermore, the emergence of the double peak of resistivity at ν = 0 state indicates spin-splitted edge state with high effective exchange field (>70 T). These phenomena suggest the appearance of topological Anderson insulator state triggered by the induced exchange field and disorder.
Highlights
Two-dimensional(2D) topological insulator has helical edge boundary due to spin-orbit coupling (SOC) and time reversal symmetry leading to quantum spin Hall (QSH) phase[1]
Near the charge neutral point (CNP) of graphene, the Anderson insulator state appeared in company with Kondo effect and it can be transited into a metallic state with a spin-splitted edge state under the high magnetic field, similar to a topological Anderson insulator (TAI) state
We showed that magnetic impurities of Fe clusters/adatoms on graphene can effectively induce strain and exchange field simultaneously
Summary
Two-dimensional(2D) topological insulator has helical edge boundary due to spin-orbit coupling (SOC) and time reversal symmetry leading to quantum spin Hall (QSH) phase[1]. This nontrivial topological phase could be emerged when disorder is added to a trivial band structure[2,3,4,5,6,7]. Disordered graphene by heavy adatoms could exhibit diverse condensed matter phenomena such as spin Hall effect and QSH state (topological insulator state) due to the instilled spin-orbit coupling and honeycomb lattice distortion. Near the charge neutral point (CNP) of graphene, the Anderson insulator state appeared in company with Kondo effect and it can be transited into a metallic state with a spin-splitted edge state under the high magnetic field, similar to a TAI state
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