Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Phase Competition in Strongly Correlated Magnetic Systems

Roger Miller

Monday, July 25, 2005
11:30 AM @ Stirling A


Strongly correlated electronic systems have presented a challenge to both theorists and experimentalists. Typically the low charge-carrier concentration and importance of electron correlations make traditional theoretical models ineffective at explaining the unusual behaviour observed in these systems, and the sharp electronic and magnetic transitions suggest a delicate balance between numerous phases, some of them undoubtedly novel. In this talk I will discuss recent research on two classes of such systems: the high temperature superconductors and the colossal magneto resistive manganites.

Using muon spin rotation, I investigate the interplay of antiferromagnetism and superconductivity in single crystals of YBa2Cu3O6+x, a commonly studied high Tc superconductor. In high magnetic fields and when the charge carrier density is heavily reduced, I show that antiferromagnetism coexists with superconductivity on a nanometer lengthscale. In the manganites, I present an initial investigation of the magnetic phase of thin films of La0.67Ca0.33MnO3 with 8Li b-NMR, a new technique designed for the study of magnetic materials on nanometer lengthscales.

The results will pave the way for research into light-induced phenomena in manganites and other materials. Both of these studies reveal the rich phase diagram of strongly correlated electronic systems, the coupling of their spin, charge and lattice degrees of freedom, and their sensitivity to external perturbations such as magnetic fields or light.

Roger Miller is a short-listed candidate for the recently-advertised position in Experimental Condensed Matter Physics.

Refreshments will be available after the talk.