Two-Stage Proximity-Induced Gap-Opening in Topological Insulator - Insulating Ferromagnet (Bi${}_x$Sb${}_{1-x}$)${}_2$Te${}_3$ - EuS Bilayers

Abstract

To further investigate the interplay between ferromagnetism and topological insulators, thin films of the low-carrier topological insulator (Bi${}_x$Sb${}_{1-x}$)${}_2$Te${}_3$ were deposited on the insulating ferromagnet EuS (100) in situ. AC susceptibility indicates magnetic anomalies between $T\approx 30\mathrm{K}$ and $T\approx 60\mathrm{K}$, well above the Curie temperature $T_C\approx 15\mathrm{K}$ of EuS. When the Fermi level is close to the Dirac point and the surface state dominates the electric conduction, sharp increases in resistance with decreasing temperatures were observed concurrently with the magnetic anomalies. Positive-negative magnetoresistance crossovers were observed at the Curie temperature, which seem only to appear when the sheet resistance exceeds the Mott-Ioffe-Regel limit $h/e^2$. A two-stage gap-opening process due to magnetic proximity is proposed.

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Cited by in corpus (5)

• Progress and prospects in the quantum anomalous Hall effect
• Absence of magnetic-proximity effect at the interface of Bi${}_2$Se${}_3$ and (Bi,Sb)${}_2$Te${}_3$ with EuS
• Evidence for exchange Dirac gap in magneto-transport of topological insulator-magnetic insulator heterostructures
• Dependence of the electronic structure of the EuS/InAs interface on the bonding configuration
• Absence of strong localization at low conductivity in the topological surface state of low disorder Sb2Te3