A magnetic field induces antiferromagnetism in a metal

9 January 2015

Dr Chris Lester and Professor Stephen Hayden of the Correlated Electrons Group at the University, together with collaborators, have found that a large magnetic field can stabilize antiferromagnetism in a metal.

Published this week in Nature Materials (http://dx.doi.org/10.1038/nmat4181) is work from the Correlated Electron Systems research group.

Lester et al. used the LET and WISH spectrometers at the ISIS Spallation source to study the oxide metal Sr₃Ru₂O₇. They found that an 8 Tesla magnetic field induced a form of antiferromagnetism known as a spin density wave at temperatures less than 1 Kelvin. The state of the spin density wave can be controlled by rotating the sample with respect to the magnetic field. This leads to large changes in the resistance of the metal.

The results have analogies with molecular systems, where phases with broken translation symmetry (such as liquid crystals, and ice) exist over a range of pressure (instead of field) bounded by isotropic phases of higher symmetry. It also suggests a new method to control the resistance of a metal in a high magnetic field.

Image left:

Over a narrow range in magnetic field near 8 T, and at temperatures below 1 K, an incommensurately-modulated spin density wave structure is stabilised in Sr₃Ru₂O₇.