University of Birmingham > Talks@bham > Condensed Matter Physics Seminars > Surface phase transitions and order in frustrated magnets

Surface phase transitions and order in frustrated magnets

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  • UserMel Hopper, University of Birmingham
  • ClockFriday 12 March 2010, 14:00-15:00
  • HousePhysics East 217.

If you have a question about this talk, please contact Elizabeth Blackburn.

I shall begin this seminar by presenting theoretical work that proposes a new type of magnetic spin reconstruction localised on the near-surface of face centred cubic magnets. I shall then open up the floor to discussion and suggestions for how this proposed phenomenon could be realised and explored in real systems.

Structural surface reconstructions are a well known phenomenon, such as that of the Silicon 7×7 surface reconstruction. Similarly, magnetic surface reconstructions can also occur as a result of altered magnetic bonding at the surface, simply due to spins losing neighbours once the surface is introduced. Until now, the reorientation has merely involved the relative intensities of Bragg spots altering with respect to one another as the surface is approached. However, in our proposed reconstruction, new symmetry appears near the surface that is different from that present in the bulk. As such, a phase transition associated solely with the surface order is expected to occur at temperatures lower than the bulk magnetic ordering temperature, a phenomenon that up until now has been thought to be unusual if not impossible.

I shall show that multiple-q magnets, and in particular face-centred cubic magnets, onto which our model can be mapped exactly, have special properties that satisfy the criteria for such a reconstruction. I shall also begin to discuss the validity of the model to real systems.

This talk is part of the Condensed Matter Physics Seminars series.

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