Magnetic Resonance Studies of Strongly Correlated Electron Materials

University Of California-Riverside, Riverside CA

Investigators

Abstract

Technical: In the muon spin rotation (muSR) technique spin-polarized muons are used as magnetic resonance probes of electronic structure and magnetism in condensed matter. This award supports a study of magnetism and superconductivity in highly correlated electron metals and alloys, where the correlations between electrons dominate the behavior. The sensitivity of muSR to atomic-scale magnetism makes this technique an ideal tool to probe local effects of these strong electron correlations. The unique Pr-based heavy-fermion superconductor PrOs4Sb12 and Pr(Os,Ru)4Sb12 alloys will be studied to elucidate the mechanism for broken time reversal symmetry in the end compound. The interplay between magnetism and superconductivity will be investigated in (Pr,Nd)Os4Sb12 alloys. The unusual spin freezing and fluctuations recently found in the highly frustrated antiferromagnets NiGa2S4 and Pr2Ir2O7 will be studied in detail. Graduate students in this program will be well prepared for research/teaching careers in both basic and applied areas. Non-Technical: In simple metals the electrons that conduct electrical currents do not affect each others' behavior very much, but correlations between electrons are important and even crucial in understanding the behavior of more complex materials, the so-called strongly-correlated electron systems. Our research uses the muSR technique, in which a short-lived subatomic particle, the muon, probes its local magnetic environment on the atomic distance scale. This work will lead to better understanding of the behavior of (1) the so-called heavy-electron metals, in which electrons act as if they were hundreds or even thousands of times more massive than free electrons, and (2) "frustrated" magnets, in which competing magnetic interactions lead to new quantum phenomena. Graduate students in this program will gain valuable insight into facility-based research at the national and international level, and will be well prepared for research/teaching careers in both basic and applied condensed-matter physics and materials research.