Searching for Exotic Quantum Phenomena in the Magnetic Structure of CeAl2 around a Quantum Critical Point

Temperature and pressure combined allow the study of a wide range of phase space and can lead to the formation of new quantum phases including unconventional superconducting states, with fascinating scientific and, based on enhanced understanding, technological potential. Our recent low temperature resistivity measurements on high purity samples of the antiferromagnet CeAl2 show evidence for a new, as yet unidentified, phase emerging in the vicinity of a quantum critical point when the antiferromagnetic order is suppressed with pressure. The aim of this proposal is to determine the low temperature, high pressure magnetic structure of CeAl2, in particular focussing on the applied pressure region around the quantum critical point. Unusually in this region we see the transformation from a metallic state to an insulating state in our recent resistivity measurements, and a linear temperature exponent of the resistivity. These results are highly surprising. To date, there is no low temperature, hydrostatic high pressure neutron magnetic structure data on CeAl2. To understand the unusual behaviour as the quantum critical point is approached, we need to determine how the magnetic structure evolves with pressure.