APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014;
Denver, Colorado
Session S39: Invited Session: Artificial Spin Ice and Artificial Frustrated Systems: Desiging Topology, Controlling Frustration, Engineering Emergence
8:00 AM–11:00 AM,
Thursday, March 6, 2014
Room: Mile High Ballroom 2A-3A
Sponsoring
Units:
DCMP GMAG
Chair: Cristiano Nisoli, Los Alamos National Laboratory
Abstract ID: BAPS.2014.MAR.S39.3
Abstract: S39.00003 : Collective Properties of Nanomagnet Arrays; Electric and Magnetic Currents in Artificial Spin Ice*
9:12 AM–9:48 AM
Preview Abstract
Abstract
Author:
Will Branford
(Department of Physics, Blackett Laboratory, Imperial College London, London SW72AZ, UK and London Centre for Nanotechnology)
I will discuss arrays of single domain nanomagnets. The shape of each
nanomagnets controls the magnetic anisotropy and the elements are closely
spaced so dipolar interactions are important. Lattices are chosen such that
the geometry prevents all dipole interactions from being satisfied. The
building block of such frustrated lattices is the equilateral triangle
because it cannot support simple antiparallel ordering. A two dimensional
array of corner sharing triangles is known as the kagome lattice and a
three-dimensional array of corner sharing tetrahedral is known as
pyrochlore. Magnetic pyrochlore chemical compounds (spin ices) have recently
attracted much attention with the observation of emergent magnetic
monopoles, but they have limitations as model frustrated systems: tuning the
lattice parameter by chemical doping tends to break the symmetry, specific
defects cannot be engineered and the spins cannot be directly imaged. The
use of frustrated artificial nanostructures overcomes these problems through
the tremendous versatility in array fabrication and compatibility with a
suite of magnetic imaging techniques.
Here I will show direct magnetic imaging studies of monopole defects [1-2]
and magnetic charge flow. [3-4] The magnetic charge is carried by transverse
domain walls and the chirality of the domain wall is found to control the
direction of propagation. In addition to magnetic imaging studies of the
magnetization state, I will also present magnetoresistance and Hall effect
measurements. These techniques probe the array as a whole and can be very
sensitive to the details of the spin structure. A change in symmetry in the
Hall response of connected honeycomb nanostructures is observed at low
temperatures indicating a collective response of the array of nanomagnets.
[5]
\\[4pt]
[1] S. Ladak, D. E. Read, G. K. Perkins, L. F. Cohen {\&} W. R. Branford.
Nature Physics 6, 359, (2010).\\[0pt]
[2] S. Ladak, D. Read, T. Tyliszczak, W. R. Branford {\&} L. F. Cohen. New
Journal of Physics 13, 023023, (2011).\\[0pt]
[3] S. Ladak, S. K. Walton, K. Zeissler, T. Tyliszczak et al. New Journal of
Physics 14, 045010, (2012).\\[0pt]
[4] K. Zeissler, S. K. Walton, S. Ladak, D. E. Read et al. Sci. Rep. 3,
01252, (2013).\\[0pt]
[5] W. R. Branford, S. Ladak, D. E. Read, K. Zeissler {\&} L. F. Cohen.
Science 335, 1597, (2012).
*Work funded by UK EPSRC Career Acceleration Fellowship and a Research Project Grant from the Leverhulme Trust
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.S39.3