15 / 23
Page 87
conferenceseries
.com
Volume 6
Research & Reviews: Journal of Material Sciences
ISSN: 2321-6212
Magnetic Materials 2018
October 22-23, 2018
October 22-23, 2018 | Rome, Italy
3
rd
International Conference on
Magnetism and Magnetic Materials
Res. Rev. J Mat. Sci. 2018, Volume 6
DOI: 10.4172/2321-6212-C6-030
Non-local spin transport in topological insulator nanowires
Jia G Lu
University of Southern California, USA
T
he momentum and spin of charge carriers in the topological insulators are constrained to be perpendicular due to strong
spin-orbit coupling. Sb
2
Te
3
is one of the topological insulator materials with a bulk band gap of 0.28 eV and simple surface
states consisting of a singleDirac cone in the band
gap.Wehave synthesized single crystalline Sb
2
Te
3
nanowires using lowpressure
catalytic chemical vapor deposition, via vapor-liquid-solid growth mechanism. Two levels of aligned e-beam lithography were
used to pattern non-magnetic outer Au leads and two magnetic tunnel junction inner leads on individual Sb
2
Te
3
nanowires.
The tunnel junction leads consist of a free Py (Ni
80
Fe
20
) layer, whose magnetization determines the magnitude and direction
of spin current injected into the Sb
2
Te
3
nanowire. Measurements of the device resistance between the two Au leads reveal that
the Au/Sb
2
Te
3
contact is ohmic. The two-point resistance measured between these contacts as a function of magnetic field
shown exhibits positive magneto-resistance, originating from weak anti-localization of carriers in the Sb
2
Te
3
nanowire induced
by spin-orbit interaction. The weak anti-localization signal serves as evidence of a strong impact of spin orbit interaction on
transport in the Sb
2
Te
3
nanowire system. We have also measured a non-local spin valve signal in Sb
2
Te
3
nanowire channels. The
symmetry of this non-local spin valve (NLSV) signal is dramatically different from that of an NLSV with a channel that lacks
spin-momentum locking (such as graphene). Two parallel states of the injector and detector magnetic moments give rise to
different non -local voltage values, which is never observed in conventional NLSVs. This unusual symmetry is a clear signature
of the spin-momentum locking in the Sb
2
Te
3
nanowire surface state.
jialu@usc.edu