Drastic changes in electronic properties of Kondo semiconductor CeRu2Al10 induced by Rh doping: Anisotropic transport properties in the antiferromagnetic ordered state
| Autor: | Fumiya Nakagawa, Hiroshi Tanida, Takashi Nishioka, Masafumi Sera, K. Yoshida, Hiroki Nohara |
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| Rok vydání: | 2016 |
| Předmět: |
Physics
Condensed matter physics Order (ring theory) Charge (physics) 01 natural sciences 010305 fluids & plasmas Electrical resistivity and conductivity Seebeck coefficient 0103 physical sciences Antiferromagnetism Condensed Matter::Strongly Correlated Electrons Orthorhombic crystal system 010306 general physics Anisotropy Spin-½ |
| Zdroj: | Physical Review B. 94 |
| ISSN: | 2469-9969 2469-9950 |
| Popis: | Electrical resistivity ($\ensuremath{\rho}$), thermopower, and specific heat measurements have been performed on the novel Kondo semiconductor $\mathrm{Ce}{({\mathrm{Ru}}_{1\ensuremath{-}x}{\mathrm{Rh}}_{x})}_{2}{\mathrm{Al}}_{10}$ ($x=0$, 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 ${\mathrm{CeRu}}_{2}{\mathrm{Al}}_{10}, \ensuremath{\rho}$ 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 $\ensuremath{\rho}$. One is an isotropic charge gap which enhances $\ensuremath{\rho}$ below ${T}_{0}$ isotropically, although its origin is not known at present. The other is an anisotropic suppression of $\ensuremath{\rho}$ 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 $\ensuremath{\rho}$ below ${T}_{0}$ is drastically changed. For $I\ensuremath{\parallel}b$, the increase is almost completely suppressed and a metallic-like behavior is observed, whereas it is small and isotropic for $I\ensuremath{\parallel}a$ 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 ${\mathrm{CeRu}}_{2}{\mathrm{Al}}_{10}$ should be viewed as unusual as the AFM order in ${\mathrm{CeRu}}_{2}{\mathrm{Al}}_{10}$ 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 (${m}_{\mathrm{AF}}$) 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 that the spin reorientation from ${m}_{\mathrm{AF}}\ensuremath{\parallel}c$ to ${m}_{\mathrm{AF}}\ensuremath{\parallel}a$ takes place quite abruptly just at ${x}_{c}\ensuremath{\sim}0.03$, which could be related to the topology change of the Fermi surfaces. |
| Databáze: | OpenAIRE |
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