APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014;
Denver, Colorado
Session M25: Focus Session: Thermoelectrics - Phonons and Heat Conduction I
11:15 AM–2:15 PM,
Wednesday, March 5, 2014
Room: 503
Sponsoring
Units:
GERA DMP
Chair: Andrew May
Abstract ID: BAPS.2014.MAR.M25.1
Abstract: M25.00001 : Phonon and magnon heat transport and drag effects
11:15 AM–11:51 AM
Preview Abstract
Abstract
Author:
Joseph P. Heremans
(The Ohio State University)
Thermoelectric generators and coolers constitute today's solid-state energy
converters. The two goals in thermoelectrics research are to enhance the
thermopower while simultaneously maintaining a high electrical conductivity
of the same material, and to minimize its lattice thermal conductivity
without affecting its electronic properties. Up to now the lattice thermal
conductivity has been minimized by using alloy scattering and, more
recently, nanostructuring [1].
In the first part of the talk, a new approach to minimize the lattice
thermal conductivity is described that affects phonon scattering much more
than electron scattering. This can be done by selecting potential
thermoelectric materials that have a very high anharmonicity, because this
property governs phonon-phonon interaction probability. Several possible
types of chemical bonds will be described that exhibit such high
anharmonicity, and particular emphasis will be put on solids with
highly-polarizable lone-pair electrons, such as the rock salt I-V-VI2
compounds (e.g. NaSbSe2).
The second part of the talk will give an introduction to a completely new
class of solid-state thermal energy converters based on spin transport. One
configuration for such energy converters is based on the recently discovered
spin-Seebeck effect (SSE). This quantity is expressed in the same units as
the conventional thermopower, and we have recently shown that it can be of
the same order of magnitude. The main advantage of SSE converters is that
the problem of optimization is now distributed over two different materials,
a ferromagnet in which a flux of magnetization is generated by a thermal
gradient, and a normal metal where the flux of magnetization is converted
into electrical power. The talk will focus on the basic physics behind the
spin-Seebeck effect. Recent developments [2] will then be described based on
phonon-drag of spin polarized electrons. This mechanism has made it possible
to reach magnitudes of SSE that are comparable to the highest values of
classical thermopower measured in semiconductors.
This work is supported as part of the Revolutionary Materials for Solid
State Energy Conversion (RMSSEC), an Energy Frontier Research Center funded
by the U.S. Department of Energy, Office of Science, by AFOSR MURI
``Cryogenic Peltier Cooling'' Contract {\#}FA9550-10-1-0533and by
NSF-CBET-1133589.
\\[4pt]
[1] J. P. Heremans {\&} al., Nature Nanotechnology\textbf{ 8,} 471-473
(2013)\\[0pt]
[2] C. M. Jaworski {\&} al., Nature, \textbf{487}, 210-213 (2012)
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.M25.1