Anomalous Magnetic Properties of URuGa

Nonmagnetic-magnetic crossover in theURu1−xPdxGasystem

“…3 Thus, the appearance of magnetism in the Pdsubstituted compositions can be explained in terms of the Kondo-lattice theory developed by Doniach 18 and other authors. 19 In their model, a critical value of the coupling parameter between localized and conduction electrons, (J sf ) cr , exists, above which the Kondo effect dominates over RKKY-type interactions, thus causing a nonmagnetic ground state.…”

“…[3][4][5] The remaining URu 1Ϫx Pd x Ga solid solutions with xϭ0.1-0.9 were synthesized by arc melting stoichiometric amounts of the constituents. The purity of U and Ga was 99.9% and that of Ru and Pd was 99.9999%.…”

“…2 In contrast to that our very recent studies of URuGa have shown that the Kondo effect plays a dominant role in this compound. 3 On the other side, UPdGa exhibits two anomalies in (T), a sharp peak at 62 K and a diffuse one at around 30 K. 4 The magnetization at temperatures below 40 K shows two steplike transitions at about 1 T and between 5 and 7 T. 4 Neutron-powder-diffraction studies of this compound have revealed a longitudinal sinusoidal structure along the c axis at low temperatures. 5 The magnetic structure between 40 K and 60 K is presently under investigation.…”

Thermal conductivity anisotropy in a ferromagnetic superconductor, UGe2

“…Recently, we have discovered around T * an unusual temperature dependence of the transverse magnetoresistivity (TMR), first for polycrystalline [5] and then for singlecrystalline [6] UGe 2 samples. The TMR measured for a UGe 2 single crystal along the three main axes was found to be highly anisotropic.…”

Ferromagnetic ordering in UFe0.5Ni0.5Al

“…In this line, we have previously investigated the magnetic properties of several such solid solutions [3][4][5][6]. Among them, UFe 1Àx Ni x Al [3] and URu 1Àx Pd x Ga [6] yield quite unexpectedly ferromagnetic properties at around x ¼ 0.5, though the end compounds are either paramagnets (UFeAl [7], URuGa [8,9]) or antiferromagnets (UNiAl [10], UPdGa [11]). …”