QUANTUM EFFECT IN MAGNETISM

从量子效应的角度研究了铈和铀金属间化合物的磁性。(1)用热膨胀和磁致伸缩的方法研究了Ce(Ru_<085>Rh_<015>)_2Si_2和U_2Rh_3Si_5的自旋-晶格耦合。由于近道效应，Ce(Ru_<085>Rh_<015>)_2Si_<2 >中Ce离子的4f^1电子由局域态转变为流动态。电子态的变化引起体积的变化。这种体积变化在重费米子系统中被解释为一种类似INVAR的效应。(2)对UPt_3和URu_2Si_2的微矩磁性进行了理论研究。(3)研究了（in, Mn）As半导体的铁磁性稳定性。(4) Ce(Ru1_<1-X>Rh_X)_2Si_2在x = 0.03、0.4和0.5处存在反铁磁态和顺磁态的临界边界。费米和非费米液体行为分别出现在x = 0.03和x = 0.4和0.5的最低温度下。用muSR研究了这些行为，发现当x = 0.03时，出现了T = 0时的磁相变，而当x = 0.4和0.5时，出现了一个负T_N的类Griffiths相。

Magnetism of Ce and U intermetallic compounds were investigated focused on quantum effects.(1)Spin-lattice coupling was studied on Ce(Ru_<085>Rh_<015>)_2Si_2 and U_2Rh_3Si_5 by mens of thermal expansion and magnetostriction. 4f^1 electron of Ce ion in Ce(Ru_<085>Rh_<015>)_2Si_<2 > changes from localized to itinerant state due to Kondo effect. The change of electronic state induces volume change. Such a volume change is interpreted as an INVAR like effect in heavy fermion system.(2) Magnetism of tiny moment in UPt_3 and URu_2Si_2 were studied theoretically.(3)Stability of ferromagnetism in (In, Mn)As semiconductor was studied.(4)There are 3 critical boundaries between antiferromagnetic and paramagnetic states which are at x = 0.03, 0.4 and 0.5 in Ce(Ru1_<1-X>Rh_X)_2Si_2. Fermi and non-Fermi liquid behaviors appear at the lowest temperatures for x = 0.03 and for x = 0.4 and 0.5, respectively. These behaviors were studied by muSR and a magneitc phase transition at T = 0 is suggested for x = 0.03 while , for x = 0.4 and 0.5, a Griffiths like phase is proposed which has a negative T_N.