| Research Abstract |
In this research project we aimed to make clear, by means of neutron diffraction method, the origin of several magnetic quantum phenomena which appear in the heavy-fermion system under high pressure. For this purpose, we started from developing a cryogenic system for neutron scattering experiment with in situ pressure-tuning mechanism, and have succeed to construct a very efficient system which allow us to repeat measurements quickly and with good accuracy in setting of the pressure.
By using this system, we have studied the response of several Kondo-lattice compounds to hydrostatic pressure, to uniaxial stress and also to the chemical pressure. A highlight of the studies is the discovery of a switching of the regime of the magnetic ordering in the pseudo-binary alloy system Ce(Ru, Rh)2(Si, Ge)2, that is, the switching between the quasi-particle SDW order and the RKKY localized spin order. Another important result is the discovery of a significant hysteresis in the antiferromagnetic order of the URu2Si2 when the uniaxial stress is cycled. This observation has given an essential information to consider the origin of the so-called "hidden order" in this compound.
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