ASANO Takayuki Kyushu University, Faculty of Science, Assistant Professor, 理学部, 助手 (00301333)
SOEJIMA Yuji Kyushu University, Faculty of Science, Associated Professor, 理学部, 助教授 (10206675)
SHIRATORI Kiichi Kyushu University, Faculty of Science, Professor, 理学部, 教授 (80028125)
|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1998 : ¥2,200,000 (Direct Cost : ¥2,200,000)
The purpose of this project is to verify experimentally and control the possible spin liquid syate which is theoretically predicted to be exist in some low dimensional magnets, due to the quantum spin ejjects and spin frustration effects. For this purpose, we synthesized a various kind of model quantum systems and applied various complementary techniques, including advanced crystal preparation, nuclear Magnetic resonance, electron spin resonance, neutron scattering, muon spin relaxation, high field magnetization as well as sysceptobility and specific heat measurements, in cooperation with many other research groups. A summary of our research is as follows.
1) Synthesis of the model substances such as S=1/2 antiferromagnetic chain Cu (C_6H_7N)_2Br_2, S=1/2 bond alternating chain Cu (C_6H_7N)_2Cl_2, S=1/2 spin ladder Cu_2(C_5H_<12>N_2)_2Cl_4, Cu_2 (C_5H_<12>N_2) _2Bra_4 and so on.
2) Study of quantum effects of composite spin systems composed of S=1/2 subelements.
For example, we performed high-frequency ESR study up to 800GHz of trimerized chain system 3CuCI_2-2dx, in which ferromagnetic trimers consisting of three S=1/2 spins coupled antiferromagnetically in one dimension. We observed peculiar behaviors characteristic of composite spin. system with nonuniform spatial structure.
3) Control of quantum spin-gappped phase.
We explored the possible induced-phase transition in the quantum singlet ground state systems with spin gap by applying high magnetic field or by doping impurity ions. For example, we observed successive phase transitions at three restricted field regions up to 40T in the S=2/3 dimerized system Cs_3Cr_2Cl_3.