Superconductivity and Magnetism of Strongly Correlated Electron Systems Studied by MuSR

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This individual investigator award funds research that aims to apply the muon spin relaxation (MuSR) technique to the study of superconductivity and magnetism in a variety of systems including; high-Tc cuprate, intercalated HfNCl, other superconductors, and low-dimensional and/or geometrically frustrated spin systems. The MuSR method will allow accurate determination of the magnetic field penetration depth in type-II superconductors, and of spontaneous magnetic fields and spin fluctuations in magnetic materials. This project will also include attempts of charge doping via the formation of field effect transistors (FET). The MuSR and FET results will elucidate the evolution from insulators to superconductors to simple metals in superconductors, and from spin singlet states to frozen spin states in magnetic systems. Emerging pictures will be considered from a unified point of view regarding crossover from gapped to ungapped states near quantum phase transitions. The project will also support highly motivated graduate students at Columbia, give them the unique experience of international collaboration, and promote a greater role of female PhD students / researchers in experimental physics. %%%During the recent 15 years, several novel superconductors with very high transition temperatures have been discovered. They include high-Tc copper oxides and intercalated HfNCl. Muon spin relaxation (MuSR) is a new and powerful experimental method for studying superconducting and magnetic properties of solids by using a beam of sub-atomic particles (Mu-meson) produced by high-intensity proton accelerators. This individual investigator award will support research in which the Columbia University group will apply the MuSR technique to studies of several high-Tc superconductors and relevant magnetic materials to elucidate how charges and spins are correlated to exhibit a variety of novel phenomena in solids. This project will provide information crucial for increasing transition temperatures, which would help in the application of high-Tc superconductors to commercial electronic devices and power cables. The project will also support highly motivated graduate students at Columbia, give them the unique experience of international collaboration, and promote a greater role of female PhD students / researchers in experimental physics.***