Pressure-Induced Magnetic Quantum Phase Transition in Gapped Spin System KCuCl<sub>3</sub>
Kenji GotoDepartment of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo 152-8551Masashi FujisawaDepartment of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo 152-8551Hidekazu TanakaResearch Center for Low Temperature Physics, Tokyo Institute of Technology, Oh-okayama, Meguro-ku, Tokyo 152-8551Yoshiya UwatokoInstitute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8581Akira OosawaDepartment of Physics, Sophia University, Kioi-cho, Chiyoda-ku, Tokyo 102-8554Toyotaka OsakabeQuantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195Kazuhisa KakuraiQuantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195
2006en
ABI
Abstract
Magnetization and neutron elastic scattering measurements under a hydrostatic pressure were performed on KCuCl3, which is a three-dimensionally coupled spin dimer system with a gapped ground state. It was found that an intradimer interaction decreases with increasing pressure, while the sum of interdimer interactions increases. This leads to the shrinkage of spin gap. A quantum phase transition from a gapped state to an antiferromagnetic state occurs at Pc ? 8.2 kbar. For P > P c, magnetic Bragg reflections were observed at reciprocal lattice points equivalent to those for the lowest magnetic excitation at zero pressure. This confirms that the spin gap decreases and closes under applied pressure.
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