Nuclear Magnetic Resonance in Condensed Matter Physics:
Nuclear Magnetic Resonance in Condensed Matter Physics: Unconventional Superconductivity, Quantum Magnetism, and Other Magnificent Tales
May 07, 2014
from 02:00 pm to 03:30 pm
|Contact Name||Hyunksik Lim|
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“More is Different”. The title of Phillip Anderson's seminal paper from 1972 epitomizes our modern perception of strongly correlated many-body systems, and, to a great extent, prophesied the wealth of new physics and relevant emergent phenomena that have unfolded in the field of condensed matter the past 40 years. With the number of synthesized novel materials ever growing, intensive research efforts aim to further our understanding of their electronic and magnetic properties, as well as to devise potential technological applications. Nuclear magnetic resonance (NMR) has constituted an invaluable tool in this quest, since it provides a local microscopic probe, sensitive to both charge and spin degrees of freedom. In this talk, I will present some of our recent NMR work in two major areas of strongly correlated electron physics, namely heavy-fermions and quantum magnetism. In particular, firstly, the concept of unconventional superconductivity in heavy-fermion materials will be introduced and our NMR investigation of the superconductor family PuMX5 (M=Co, Rh; X=In, Ga) will be presented. The specific goal is to shed light on the pairing mechanism of the superconducting condensate in this class of materials: Is superconductivity mediated by spin or valence fluctuations, or is a more complicated, “composite” order parameter realized? Secondly, the effects of geometric frustration in quantum magnets will be discussed, as manifested in the triangular-lattice antiferromagnet (TLAF) Ba3CoSb2O9. Our NMR studies provide a comprehensive picture of the magnetic phase diagram for this prototypical spin-1/2 TLAF and a detailed description of its various exotic magnetically ordered states. Finally, I will briefly talk about our recent discovery of the long-sought 239Pu NMR signal, a finding that opens new frontiers for the study of plutonium in the fields of solid state physics, chemistry and materials science.