Frustration in Magnetic Oxides
Supervisor Martin Lees, Co-supervisor Oleg Petrenko
Superconductivity and Magnetism Group
Physics Department, University of Warwick
Department of Physics (www2.warwick.ac.uk/fac/sci/physics)
University of Warwick (www2.warwick.ac.uk)
Superconductivity and Magnetism Groups (go.warwick.ac.uk/supermag)
In simple magnetic materials the magnetic behaviour is
usually governed by the strength and sign of the
interactions between the magnetic moments in the
system. In frustrated magnets the competing
interactions between the moments cannot all be
satisfied simultaneously.
Studies of frustrated magnetic oxides have resulted in
the discovery of some exciting new physics including
spin ice and monopoles (see Fig 1.). Many of these
breakthroughs have opened new avenues of research,
while others have raised important questions that
remain unanswered. It is the physics of these systems
that will be the focus of this project. For some of our
recent work please see Refs. 1 to 3.
Fig. 1 Phase diagram as a function of temperature T and
the relative strength of the planar and Ising exchange for
some pyrochlore titanates. Ho2Ti2O7 and Dy2Ti2O7 are
spin ice while Yb2Ti2O7 undergoes a first-order transition
from a Coulomb liquid to a Higgs phase of magnetic
monopoles [1].
In this project, you will use image furnaces to grow high quality single crystals of oxide materials. The
structural properties of these frustrated materials will be studied using a suite of state-of-the-art xray spectrometers and electron microscopes. You will examine the magnetic properties of these
crystals in the laboratory at low temperatures and in high magnetic fields. You will also use a range
of neutron scattering and muon spectroscopy techniques at national and international central
facilities to investigate the physics of these materials.
This experimental project will offer an excellent training in several important aspects of modern
condensed matter physics.
[1] L.-J. Chang, S. Onoda, Y. Su, Y.-J. Kao, K.-D. Tsuei, Y. Yasui, K. Kakurai, M. R. Lees, Nature Communications 3, 992 (2012).
[2] L.-J. Chang, M. R. Lees, I. Watanabe, A. D. Hillier, Y. Yasui, S. Onoda, Physical Review B 89, 184416 (2014).
[3] E. Lhotel, S. R. Giblin, M. R. Lees, G. Balakrishnan, L. J. Chang, Y. Yasui, Physical Review B 89, 224419 (2014).