H. Sugawara

Magnetic properties of single crystal CeFe2Ge2

Abstract We have grown a single crystal of CeFe 2 Ge 2 by a Czochralski pulling method in a tetra-arc furnace. The electrical resistivity and magnetic susceptibility are highly anisotropic, which is similar to CeRu 2 Si 2 . The electronic specific heat coefficient is 210 mJ/K 2 mol, indicating a heavy electron system with a non-magnetic ground state. These experimental results, including the magnetoresistance, are compared to those of LaFe 2 Ge 2 .

De Haas-van Alphen studies of rare earth compounds

Abstract The de Haas-van Alphen amplitude of branch d in CeIn3 is reduced with oscillation by three orders of magnitude when the field is tilted from 〈100〉 to 〈110〉 in the {100} plane. This is explained by considering the angular dependence of the cyclotron mass and the electron spin g-factor.

Change of the Fermi surfaces at the magnetic transition in NdIn3

Abstract We have done de Haas-van Alphen experiments for NdIn3 in high fields up to 17 T. The drastic change of the Fermi surfaces at the metamagnetic transition is presented.

Anomalous Hall Coefficient in the f Electron System

The 4f(5f) electrons in the rare earth(uranium) atom are pushed deep into the interior of the closed 5s(6s) and 5p(6p) shells because of the strong centrifugal potential 1(1+1)/r2 , where 1=3 holds for the f electrons. This is a reason why the 4f (5f) electrons possess an atomic-like character even in the compound. On the other hand, the tail of their wave function spreads to the outside of the closed 5s(6s) and 5p(6p) shells, which is highly influenced by the potential energy, the relativistic effect, the distance between the rare earth(uranium) atoms, and hybridization of the 4f(5f) electrons with the conduction electrons. These cause the various phenomena such as valence and spin fluctuations, gap states, Kondo lattice, heavy electrons (fermion), metamagnetism and superconductivity for the f electron compounds.1

Elastic constants of LaRh2 and CeRh2

Temperature dependence of the elastic constants are measured for single crystals of LaRh 2 and CeRh 2 . The constants c 11 and (c 11 −c 12 )/2 for CeRh 2 show monotonous temperature dependence, and a very shallow minimum is found around 70 K in c 44 . This result show no evidence on the crystal field effect and may suggest the itinerant nature of 4f-electrons in CeRh 2 . LaRh 2 shows a remarkable softening below 50 K in c 44 . The anomalous temperature dependence of elastic constants in LaRh 2 is discussed based on the band effect

Metamagnetic transition in PrCu2

Abstract We have observed a metamagnetic transition in PrCu 2 where there is a cooperative Jahn-Teller effect occurring below 8 K. This transition brings about a large crystal distortion and also a drastic change of the electronic state, namely the Fermi surface.

Single crystal growth and superconducting properties of CeRu2

Abstract We have grown a single crystal of the superconductor CeRu2 by a zone-melting method in an induction furnace. We have measured the lower and upper superconducting critical fields, which are estimated as 250–400 Oe and 74 kOe at 0 K, respectively. Hc2 is slightly anisotropic, 64.8 kOe for the field along the 〈1 0 0〉 direction and 65.6 kOe for 〈1 1 0〉 at 1.5 K. The anomaly in the magnetization below Hc2 reported by another group was also investigated.

Fermi surfaces of YRu2Si2 and LaRu2Si2

Abstract We have measured the de Haas-van Alphen effect of YRu 2 Si 2 and LaRu 2 Si 2 to clarify the Fermi surfaces and cyclotron masses. Main hole-Fermi surfaces of both compounds with a distorted ellipsoid shape are similar, occupying about half of the Brillouin zone. The small hole-Fermi surfaces with the shape of a rugby ball are three in number for LaRu 2 Si 2 , and one for YRu 2 Si 2 . An electron-Fermi surface consists of a doughnut like shape for LaRu 2 Si 2 , while a cylinder along the [0 0 1] direction and a multiply-connected shape exist for YRu 2 Si 2 . The cyclotron masses of YRu 2 Si 2 are a little larger than those of LaRu 2 Si 2 .

High field magnetization of a NdCu2 single crystal

Abstract Studies of the high-field magnetization on a single crystal of NdCu 2 with the field along the three principal crystallographic directions are presented. A crossing of the magnetization curves along the a - and b -axes is observed. The order of magnetization along each axis in high magnetic fields is then ( μ c μ b μ a ). This behaviour is discussed in terms of a microscopic hamiltonian including crystal-field and Zeeman interactions.

Single-crystal growth and Fermi surface properties of LaRh2

Abstract We have succeeded in growing a single crystal of LaRh 2 by a zone-melting method in a cold crucible under a high vacuum of 1 × 10 -8 Torr. The Fermi surface properties of LaRh 2 are discussed on the basis of the de Haas-van Alphen effect.