UCL Quantum Science and Technology Institute


UCLQ Visitor Lecture Series – Joaquin Fernandez Rossier

17 March 2015, 3:00 pm–4:00 pm

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UCL Quantum

I am very pleased to announce that Joaquin Fernandez Rossier from INL will be giving a seminar next week on his work. The talk is part of the UCLQ series and will be accessible to all researchers.

Title: Robust orbital nanomagnets

Abstract: I discuss a new type of nanomagnet for which the dominant  contribution to magnetization comes from orbital degrees of freedom,  in contrast with usual systems.  Here I  discuss our proposal  that nanoislands of quantum spin Hall insulators can host robust orbital edge magnetism whenever  a single electron, as opposed to 0 or 2,  resides at the  highest occupied Kramers doublet  upgrading the spin edge current  into  a charge current.  The resulting    orbital magnetization scales linearly with size,  outweighing the spin contribution for islands of a few nm in size.    This linear scaling is a specific  of  the Dirac edge states,    different from  Schrodinger electrons in quantum rings. Modelling Bi(111) flakes,  whose edge states have been recently observed [2],  we show that orbital magnetization is robust with respect to disorder, thermal agitation,  shape of the island and crystallographic direction of the edges, reflecting its topological protection.  I discuss the  notion of spin amplification using this type of system,  that would permit single spin readout .


[1] P. Potasz,  J. Fernandez-Rossier, in preparation
[2] Ilya K. Drozdov, A. Alexandradinata, Sangjun Jeon, Stevan Nadj-Perge, Huiwen Ji, R. J. Cava, B. A. Bernevig, Ali Yazdani, Nature Physics 10, 663-669 (2014).