Frustrated random-singlet state with ice-type structural fluctuation in spinel titanates
Abstract
In ice, it is well known that the orientation of H 2 O molecules is disordered by geometrical frustration. Ice-analogous materials having a pyrochlore lattice display interesting phenomena such as the spin-ice state and the magnetic monopole. In the spinel titanate MgTi 2 O 4 , the Ti ions have a quantum spin in the pyrochlore lattice. The Ti ions are displaced, accompanied by the spin-singlet formation. Since this displacement pattern follows the ice rule, the title compound is a material analogous to ice. When a small quantity of Ti ions are replaced with Mg ions, the ice-type structural fluctuation exists. In this structural ice-type state, the spins are also fluctuating at a nanosecond scale down to 0.3 K. We ascribed this phenomenon to the gapless frustrated random-singlet state, in which the spin-singlet pairs are resonating, and the orphan spins are hopping.
Article Details
Journal Info
Proceedings of the National Academy of Sciences
National Academy of Sciences
Authors (20)
Noriaki Hanasaki
Department of Physics
Takayuki Hattori
Department of Physics, University of Osaka
Takumi Komoda
Department of Physics, University of Osaka
Kouei Minamoto
Department of Physics, University of Osaka
Shuhei Torigoe
Department of Physics, University of Osaka
Satoshi Yamashita
Yasuhiro Nakazawa
Takehito Nakano
Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University
Kouhei Yoshimi
Graduate School of Engineering Science, University of Osaka
Mitsuharu Yashima
Graduate School of Engineering Science, University of Osaka
Hidekazu Mukuda
Graduate School of Engineering Science, University of Osaka
Utami Widyaiswari
Nuclear Structure Research Group, RIKEN Nishina Center
Isao Watanabe
Nuclear Structure Research Group, RIKEN Nishina Center
Akihiro Koda
Institute of Materials Structure Science, High Energy Accelerator Research Organization
Takashi Honda
J-PARC Center, High Energy Accelerator Research Organization (KEK), Tokai, Ibaraki 319-1106, Japan
Toshiya Otomo
Institute of Materials Structure Science
Hajime Sagayama
Katsuaki Kodama
Materials Sciences Research Center, Japan Atomic Energy Agency
Hiroshi Murakawa
Department of Physics
Hideaki Sakai
Department of Physics