The Waterloo Institute for Nanotechnology (WIN) presents a Distinguished Lecture by Dr Kang L. Wang, Distinguished Professor and Raytheon Chair Professor in Physical Science and Electronics in the Electrical Engineering Department of the University of California, Los Angeles (UCLA), United States.
Lecture: 3:00-4:00pm
Reception: 4:00-5:00pm
Spin-Orbitronics for Energy Efficient Systems
Abstract
Energy dissipation has become the major challenge for the current electronics. This is due to the leakage current and the voltage scaling limit of nanoscale structures. With nonvolatile magnetic memory and alike, the leakage current may be minimized and the voltage scaling can be further advanced due to the collective behavior of magnetism. Meanwhile, spin-orbit coupling (SOC), a relativistic effect which describes the coupling between the orbital and spin degrees of freedom, has become the spotlight in the field dubbed as spin-orbitronics.
In continuing effort to resolve these challenges, I will first discuss the engineering of interface SOC to illustrate the efficient control of magnetic memory, in addition to the present approach of channel and tunneling barrier engineering. The engineering of SOC results in the electric field control of magnetic moment or magneto-electric (ME) effect, which results in orders of magnitude lower energy dissipation compared with the current spin transfer torque memory (STTRAM). Likewise, the large SOC is also shown to give rise to a large spin-orbit torque or SOT. Due to the presence of an intrinsic extraordinarily strong SOC and spin-momentum lock, topological insulators (TIs) are expected to be promising candidates for exploring spin-orbit torque (SOT)-related physics. I will show magnetization switching in a chromium-doped magnetic TI bilayer heterostructure by charge current. A giant SOT of more than three orders of magnitude larger than those reported in heavy metals is also obtained. The integration of these types of spintronics devices with CMOS may resolve the two major limits and nanoarchitectures incorporating these memory devices for intelligent systems will be discussed. This large SOT deriving from the spin-momentum locked surface states of TI may be used to improve the energy efficiency for other applications.
Dr. Kang L. Wang
Kang
L.
Wang
is
currently
a
Distinguished
Professor
and
holds
Raytheon
Chair
Professor
in
Physical
Science
and
Electronics
in
the
Electrical
Engineering
Department
of
the
University
of
California,
Los
Angeles
(UCLA).
He
received
his
BS
degree
from
National
Cheng
Kung
University
(Taiwan)
and
his
MS
and
PhD
degrees
from
the
Massachusetts
Institute
of
Technology.
He
is
a
Fellow
of
the
IEEE
and
a
member
of
the
American
Physical
Society.
He
also
served
as
the
Editor-in-Chief
of
IEEE
TNANO
as
well
as
the
Editors
of
Artech
House
and
other
publications.
His
research
areas
include
nanoscale
physics
and
materials,
topological
insulators,
and,
spintronics
and
devices.
*The work was in part supported by ERFC-SHINES, ARO, TANMS, and FAME