报告题目：Correlations, Fluctuations, and Disorder at Chromium’s Quantum Phase Transition

报 告 人：Thomas F. Rosenbaum, President of California Institute of Technology

报告时间：2015年3月18日10:00

报告地点：理科楼郑裕彤大讲堂

报告摘要：We use hydrostatic pressure to suppress the magnetism in elemental chromium, a simple cubic metal that demonstrates a subtle form of itinerant antiferromagnetism, formally equivalent to the Bardeen-Cooper-Schrieffer (BCS) state in superconductors. By directly measuring the associated charge order with x-rays in a diamond anvil cell at low temperature, we reveal a phase transition at pressures ~ 10 GPa that destroys the BCS-like state while preserving the strong magnetic interaction between itinerant electrons and holes. Complementary transport results on both Cr and Cr doped with V expose a crossover to a narrow, fluctuation-dominated quantum critical regime. Cr is unique among stoichiometric magnetic metals studied to date in that its quantum phase transition is continuous in nature. This opens up experimental access to the naked quantum singularity, and a direct probe of the competition between conventional and exotic order in a theoretically tractable material.