Exp. No.

M1670 — Approved

Title of Experiment

μSR search for fluctuating loop currents in cuprates

Spokesperson(s) for Group

Safety Coordinator(s) for Group

Current Members of Group

Name Institution Status % of research time devoted to experiment
L. Shu Fudan University Associate Professor
Z. F. Ding Fudan University Student (Graduate)
K. Huang Fudan University PDF
D.E. MacLaughlin University of California, Riverside Professor Emeritus
J.E. Sonier Simon Fraser University Professor
C. Tan Fudan University Student (Graduate)
J. Zhang Fudan University Student (Graduate)


The origin of a mysterious pseudogap region in high-Tc superconductors is a challenging issue. It was proposed that the pseudogap is caused by a circulating-current order characterized by an unique long-range patten of loop currents in the CuO2 planes. Loop-current order is by now inferred in 5 different classes of symmetry-sensitive experiments: polarized neutron scattering, Kerr effect, bireferingence, dichroic ARPES, and second harmonic generation. However, local probes such as MuSR and NMR do not see the magnetic fields expected for such an order. These local probes have much longer time scales than the others. It has been suggested that the local magnetic fields may be motionally narrowed by fluctuations among the different possible directions of the loop-current order. We propose MuSR experiments to definitively test this possibility and also obtain the fluctuation time-scale.