Physicist Graeme Luke’s research interests are in the area of highly correlated electron systems, with an emphasis on superconductivity and magnetism.
He has primarily used the microscopic technique of muon spin relaxation (µSR) in conjunction with bulk methods such as AC/DC-susceptibility, resistivity and specific heat, to study the magnetic and electronic properties of highly correlated electron systems, including various exotic superconductors and geometrically frustrated antiferromagnets. The µSR experiments are mainly performed at the TRIUMF facility in Vancouver. Luke is also actively involved in the growth of large, high-quality single crystals of new materials.
The sensitivity of µSR to magnetism has aided in the development and understanding of the electronic phase diagrams of high-temperature superconductors. Measurements of the magnetic field penetration depth and spin susceptibility obtained from µSR provide direct information on the underlying symmetry of the superconducting state in cuprate, organic, heavy-fermion and conventional superconductors.
In some types of materials, magnetic ordering can be frustrated by the geometry of the underlying lattice; a simple example is that of antiferromagnetic spins on a triangular lattice. This frustration can lead to interesting dynamic behaviour. Using µSR, Luke studies these dynamics in a unique frequency range, between those accessible to neutron scattering and AC-susceptibility.
Luke, G.M. et al. "Time-reversal symmetry breaking superconductivity in Sr2RuO4." Nature 394 (1998): 558–61.
Yu, W. et al. "Absence of superconductivity in single-phase CaFe2As2 under hydrostatic pressure." Phys. Rev. B 79 (2009): 020511.
Schmidt, A.R. et al. "Imaging the Fano lattice to ‘hidden order’ transition in URu2Si2." Nature 465 (2010): 570–76.
Luke, G.M. et al. "Magnetic Order and Electronic Phase-Diagrams of Electron-doped Copper-oxide Materials." Phys. Rev. B 42 (1990): 7981–7988.
Dunsiger, S.R. et al. "Spin Ice: Magnetic Excitations without Monopole Signatures Using Muon Spin Rotation." Phys. Rev. Lett. 107 (2011): 207207.