Volume 109, Number 5, March 2015
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||12 March 2015|
Quantum Hall bilayer as pseudospin magnet
1 Division of Physics and Applied Physics, Nanyang Technological University - 637371, Singapore
2 Science Institute, University of Iceland - Dunhagi-3, IS-107, Reykjavik, Iceland
3 Niels Bohr Institute, University of Copenhagen - Blegdamsvej 17, DK-2100 Copenhagen, Denmark
4 ITMO University - St. Petersburg 197101, Russia
Received: 29 September 2014
Accepted: 16 February 2015
We revisit the physics of electron gas bilayers in the quantum Hall regime (MacDonald A. and Eisenstein J., Nature, 432 (2004) 691; Eisenstein J., Science, 305 (2004) 950), where transport and tunneling measurements provided evidence of a superfluid phase being present in the system. Previously, this behavior was explained by the possible formation of a BEC of excitons in the half-filled electron bilayers, where empty states play the role of holes. We discuss the fundamental difficulties with this scenario, and propose an alternative approach based on a treatment of the system as a pseudospin magnet. We show that the experimentally observed tunneling peak can be linked to the XY ferromagnet (FM) to Ising antiferromagnet (AFM) phase transition of the S = 1/2 XXZ pseudospin model, driven by the change in total electron density. This transition is accompanied by a qualitative change in the nature of the low-energy spin wave dispersion from a gapless linear mode in the XY-FM phase to a gapped, quadratic mode in the Ising AFM phase.
PACS: 73.43.-f – Quantum Hall effects / 73.21.Ac – Multilayers / 73.43.Nq – Quantum phase transitions
© EPLA, 2015
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.