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"ANNULLATO ---- Magnetic Charge Transport in Spin Ice"

Relatore: Sean Giblin- ISIS, Rutherford Appleton Laboratory

Aula Newton
14 Giugno 2011 ore 16.30

The recent discovery of magnetic charge in spin ice raises the question of whether long-lived currents of magnetic `monopoles' can be created and manipulated by applying magnetic fields. Here we show that they can; by applying a magnetic field pulse to a Dy_2 Ti_2 O_7 spin ice crystal at 0.36 Kelvin, we create a relaxing magnetic current that lasts for several minutes. We measure the current by means of the electromotive force it induces in a solenoid coupled to a susceptometer and quantitatively describe it using a chemical kinetic model of point-like charges obeying the Onsager-Wien mechanism of carrier dissociation and recombination. Further recent magnetic results are also discussed which support our initial conclusions.