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CAMP: Quantum anomalous Hall state and dissipationless chiral edge current in Vanadium doped (Bi, Sb)2Te3

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Weiwei Zhao, Pennsylvania State University
When
29 September 2015 from 3:30 PM to 4:30 PM
Where
339 Davey Laboratory
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The first observation of the quantum anomalous Hall (QAH) effect in ferromagnetic topological insulator Cr-doped (Bi,Sb)2Te3 films was reported in 2013. In this talk, I will focus on the experimental observation of the QAH state in a different ferromagnetic topological insulator system, namely V-doped (Bi,Sb)2Te3 films. Hall resistance of 1.00019±0.00069h/e2 (25.8178±0.0177kΩ) and the zero-field longitudinal resistance down to 0.00013±0.00007h/e2 (~3.35±1.76Ω) at T=25mK was found in this material precisely realized the QAH state [1]. We carried out a comprehensive experimental study of the gate and temperature dependences of local and nonlocal magnetoresistance in the same system, and the zero-field dissipationless chiral edge transport has unambiguously been established. By studying the onset of dissipation, the origin of dissipative channels has also been identified and it clarifies the surprising observation that the critical temperature of the QAH effect is two orders of magnitude smaller than the Curie temperature of ferromagnetism [2].

 

[1] Nature Materials 14, 473 (2015).

[2] Phys. Rev. Lett. 115,057206 (2015)

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