Yoshizawa, Hideki
Professor
Neutron Science Laboratory
University of Tokyo
Japan
Biography
Metal-insulator transition in transition-metal oxides has drawn much attention because such a phenomenon reflects interplay among spin, charge, lattice, and orbital degrees of freedom. Our group has been studying their behavior by neutron scattering technique with use of pulse and steady-source neutron beams, and the triple axis neutron spectrometer owned by the ISSP is shown in the left bottom figure. The hole-doping dependences of the incommensurability and the transition temperature of the stripe ordering for hole concentration x up to x = 0.5 have been observed in the highly-doped La2-xSrxNiO4 which is one of the isomorphic compounds of the High Tc cuprate superconductors. The ordering temperatures of the stripe charge as well as spin orderings have the maxima at x = 1/3, and they decrease beyond x = 1/3. Beyond x = 1/2, the Ni system gradually becomes metallic and show the insulator to metal transition at x ~ 0.9. Our recent pulse neutron studies on the Ni system revealed that the characteristics of the spin dynamics changes at x = 0.5, and further detail studies of such unusual spin dynamics and their relation to the transport properties are now ongoing.
Research Interest
Neutron scattering study of metal-insulator transition, magnetic ordering, charge/orbital orderings in transition-metal oxides Neutron scattering study of spin sturucture and dynamics in noncentrosymmetric magnetic superconductors
Publications
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Weak Ferromagnetism and Multiple Metamagnetic Transitions in the Non-centrosymmetric Tetragonal Compound CePdSi3: D. Ueta, Y. Ikeda and H. Yoshizawa, J. Phys. Soc. Jpn. 85 (2016) 104703.
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Superconductivity and Non-Fermi-Liquid Behavior in the Heavy-Fermion Compound CeCo1−xNixIn5: R. Otaka, M. Yokoyama, H. Mashiko, T. Hasegawa, Y. Shimizu, Y. Ikeda, K. Tenya, S. Nakamura, D. Ueta, H. Yoshizawa and T. Sakakibara, J. Phys. Soc. Jpn. 85 (2016) 094713.
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Inelastic Neutron Scattering Study of Stripe and Overdoped Checkerboard Ordering in Layered Nickel Oxide Nd2−xSrxNiO4: Y. Ikeda, S. Suzuki, T. Nakabayashi, H. Yoshizawa, T. Yokoo and S. Itoh, J. Phys. Soc. Jpn. 85 (2016) 023701.
