Joint Research on Quantum Effects in Magnetic Systems

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It is the aim of the present project to clarify the quantum phenomena in one-dimensional magnetic systems and related materials in collaboration with French and German scientists. Some of the important findings obtained from this project are summarized below :(1)In collaboration with the scientists at the Brookhaven National Laboratory in the United States, the magnetic excitation spectra in the S=1 one-dimensional antiferromagnet NINO and NINO with Cu impurities have been measured. The Haldna gap energy in NINO does not change with Cu doping, whereas the correlation length becomes shorter with Cu impurity.(2)In collaboration with the scientists at the Hahn-Meitner Institute in Germany, the magnetic properties of an S=2 quasi-one dimensional antiferromagnet CrCl_2 have been studied. A new phase transition has been observed below the Neel temperature. The magnetic excitation spectra have been measured and two gap energies are observed.(3)Samples of an S=1/2 quasi-one dimensional antiferromagnet and related compounds have been synthesized and their magnetic properties have been measured. A large reduction of the magnetic moment due to quantum fluctuation has been observed. In collaboration with the scientists at the Brookhaven National Laboratory in the United States, the magnetic excitation spectra in these samples habe been measured.(4)In collaboration with the scientist at the University of Paris in France, electron spin resonance measurements have been done on the S=5/2 quasi-one dimensional antiferromagnet TMMC.A large shift of the resonance point from the classical value has been observed.