Magnetic Resonance Studies of Strongly-Correlated Electron Materials

University Of California-Riverside, Riverside CA

Investigators

Abstract

Nuclear magnetic resonance (NMR) and muon spin rotation (muSR) techniques will be used to study electronic structure, magnetism, and superconductivity in strongly correlated electron metals and alloys. The sensitivity of NMR and muSR to magnetism on the atomic scale makes these techniques ideal tools to probe local effects of strong electron correlation. Particular attention will be paid to the crucial role of structural disorder in the non-Fermi-liquid (NFL) behavior of many heavy-fermion systems. NMR and muSR spectra and spin-lattice relaxation rates will probe inhomogeneous paramagnetism and glassy low-frequency spin fluctuations in UCu5-xPdx and other NFL systems. 27Al NMR and muSR spectra relaxation rates in Ce1-xLaxAl system will be examined for evidence whether, as recently claimed, these alloys exhibit an anisotropic Kondo effect. A thorough examination of superconductivity and magnetism will be carried out in the newly-discovered class of CenTIn3n+2 heavy-fermion materials, which exhibit a wide variety of anomalous magnetic and superconducting behavior. Other projects include muSR studies of cuprate and maganite transition metal oxides, and quantum critical behavior in MnSi under pressure. Graduate students in this program will be bell prepared for research/teaching careers in both basic and applied areas. Understanding effects of correlations between electrons on magnetism and conduction in solids remains an important unsolved problem in condensed matter physics, with practical consequences for technology in several areas of materials science. This research uses magnetic resonance techniques as probes of correlated-electron behavior at the atomic level. In magnetic resonance, the magnetism of 'spin probes' (e. g. nuclei as nuclear magnetic resonance) is used to 'spy' on the local magnetic environment of the probes, which observe but do not seriously perturb their surroundings. This work will lead to better understanding of the behavior of the so-called heavy-electron metals, in which electrons behave as if they were hundreds or even thousands of times more massive than free electrons. It will be carried out in collaboration with researchers at the Los Alamos National Laboratory, and with research trips abroad (Leiden University, ETH Zurich, TU Munich, TRIUMF, Vancouver, and Paul Scherrer Institute, Switzerland). Graduate students in this program will there for gain valuable insight into 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.