科研之友
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摘要
Electrical resistivity (rho), thermopower, and specific heat measurements have been performed on the novel Kondo semiconductor Ce(Ru1-xRhx)(2)Al-10 (x = 0, 0.02, 0.03, and 0.05), which has been attracting a great deal of interest due to an unusual antiferromagnetic (AFM) order below T-0, in order to clarify the Rh doping effect on the anisotropy of the electronic properties in the ordered state. In CeRu2Al10, rho shows an anisotropic increase below T-0 independently of the electric current direction. We propose the existence of two different mechanisms to explain the anisotropic increase of rho. One is an isotropic charge gap which enhances. below T-0 isotropically, although its origin is not known at present. The other is an anisotropic suppression of. which originates from the anisotropic c-f hybridization and is largest along the orthorhombic a axis. By the Rh doping, the anisotropic temperature dependence of rho below T-0 is drastically changed. For I parallel to b, the increase is almost completely suppressed and a metallic-like behavior is observed, whereas it is small and isotropic for I parallel to a and c. From these results, we propose that as a result of the destruction of the spin-gap excitation by the Rh doping, a metallic-like electronic state is formed along the b axis and the small isotropic charge gap is opened in the ac plane. By taking into account the present results and the still high T-0 even in x = 0.05, we conclude that the AFM order in the Rh-doped CeRu2Al10 should be viewed as unusual as the AFM order in CeRu2Al10 although the localized character of the Ce-4f electron is apparently enhanced by the Rh doping. We have also examined the evolution of the AFM ordered state from x = 0 to x = 0.05, where the AFM ordered moment (m(AF)) is aligned along the c axis in x = 0 and a axis in x = 0.05. From the results of those experiments in magnetic field, we have revealed t
- 出版日期2016-10-17
