APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014;
Denver, Colorado
Session Y48: Invited Session: Spin Transport in Novel 2d Electronic Systems
8:00 AM–10:24 AM,
Friday, March 7, 2014
Room: Mile High Ballroom 1A-1B
Sponsoring
Units:
GMAG DCMP
Chair: Berend Jonker, Naval Research Laboratory
Abstract ID: BAPS.2014.MAR.Y48.2
Abstract: Y48.00002 : Direct electrical detection of spin-momentum locking in the topological insulator Bi$_{2}$Se$_{3}$
8:36 AM–9:12 AM
Preview Abstract
Abstract
Author:
Connie H. Li
(Naval Research Lab)
Topological insulators (TIs) are a new quantum state of matter [1]
characterized by metallic surface states populated by massless Dirac
fermions. TIs are expected to exhibit new behaviors and open horizons for
science previously inaccessible with ``conventional''
materials. One of the most striking properties is
that \textit{of spin-momentum locking} -- the spin of the TI surface state lies in-plane, and is locked at
right angle to the carrier momentum. An unpolarized charge current should
thus create a net spin polarization whose amplitude and orientation are
controlled by the charge current. This remarkable property has been
anticipated by theory [2], but never accessed in a simple transport
structure. Here we show that a bias current indeed produces a net surface
state spin polarization \textit{via} spin-momentum locking in molecular beam epitaxially
grown Bi$_{2}$Se$_{3}$ films, and this polarization is
directly manifested as a voltage on a ferromagnetic metal contact. This
voltage is proportional to the projection of the TI spin polarization onto
the contact magnetization, is determined by the direction and magnitude of
the bias current, scales inversely with Bi$_{2}$Se$_{3}$
film thickness, and its sign is that expected from spin-momentum locking
rather than a Rashba effect [3]. Similar data are obtained for structures
with two different ferromagnet/tunnel barrier contacts, demonstrating that
these behaviors are independent of the details of the detector contact.
These results demonstrate direct electrical access to the TI surface state
spin system and enable utilization of its remarkable properties for future
technological applications.\\[4pt]
[1] J. E. Moore, Nature \textbf{464}, 194 (2010); M. Z. Hasan et. al., Rev. Mod. Phys. \textbf{82,} 3045 (2010); L. Fu et. al., PRL \textbf{98}, 106803 (2007); D. Hsieh et. al., Nature \textbf{452}, 970 (2008).\\[0pt]
[2] A. A. Burkov et. al. PRL \textbf{105}, 066802 (2010); D. Culcer et. al., PRB \textbf{82}, 155457 (2010); V. Yazyev et. al., PRL \textbf{105}, 266806 (2010).\\[0pt]
[3] S. Hong et. al., PRB \textbf{86}, 085131 (2012).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.Y48.2