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Prof. Takei's paper

“ Education is the most powerful weapon which you can use to change the world. ”
- Nelson Mandela
Jul 17, '17
Spin Superfluidity in the nu=0 Quantum Hall State of Graphene, So Takei, Amir Yacoby, Bertrand I. Halperin and Yaroslav Tserkovnyak, Phys. Rev. Lett., 116, 216801 (2016).
 Graphene in the quantum Hall regime provides a useful platform to study broken-symmetry phases in interacting electronic systems. Coulomb interaction lifts the fourfold spin-valley degeneracy of the graphene Landau levels, and can generate novel quantum Hall states with broken spin and/or valley symmetry. Theoretical analysis shows that the nu=0 quantum Hall ground state is in an insulating antiferromagnetic state [1]. While recent magnetotransport experiments report consistent findings, the available evidence still remains indirect [2].
 
In this paper, Prof. Takei and his collaborators show that the purported antiferromagnetic state supports nearly dissipationless (superfluid) transport of spin angular momentum through its bulk, and how such transport can be realized and detected using spin-polarized quantum Hall edge states. The detection of this phenomenon will constitute a direct evidence for the antiferromagnetic scenario of the nu=0 quantum Hall state.
 
[1] M. Kharitonov, Phys. Rev. B 85, 155439 (2012).
[2] A. F. Young, J. D. Sanchez-Yamagishi, B. Hunt, S. H. Choi, K. Watanabe, T. Taniguchi, R. C. Ashoori, and P. Jarillo-Herrero, Nature 505, 528 (2014).