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We performed the 27AI NMR on CeRu2Al10 single crystal, which exhibits the unusual phase transition at T0 = 27 K. Below T0, the NMR lines split into two lines site-selectively depending on the magnetic-field direction. The NMR spectrum shows different types of splitting below and above H* ∼ 4 T for Hext || c where a metamagneticlike transition is observed. The results measured at resonance field of H0 ∼ 2.8 T were consistent with the antiferromagnetic ordered moment (mAF) parallel to the c axis proposed by neutron-scattering experiments. The results at H0 ∼ 4.4 T indicates that mAF || b is realized above H* for Hext || c, which was unexpected from the extremely small magnitude of ᵪb. As the origin of the unusual spin-flop transition from mAF || c to mAF || b at H*, we propose that the strong c-f hybridization along the a axis prevents mAF from aligning along the a axis, and mAF is confined to the bc plane. [ABSTRACT FROM AUTHOR]

Electrical resistivity (σ), thermopower, and specific heat measurements have been performed on the novel Kondo semiconductor Ce(Ru1-xRhx)2Al10 (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 T0, in order to clarify the Rh doping effect on the anisotropy of the electronic properties in the ordered state. In CeRu2Al10, σ shows an anisotropic increase below T0 independently of the electric current direction. We propose the existence of two different mechanisms to explain the anisotropic increase of σ. One is an isotropic charge gap which enhances σ below T0 isotropically, although its origin is not known at present. The other is an anisotropic suppression of σ 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 σ below T0 is drastically changed. For I||b, the increase is almost completely suppressed and a metallic-like behavior is observed, whereas it is small and isotropic for I||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 T0 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 (mAF) 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 mAF||c to mAF||a takes place quite abruptly just at xc~0.03, which could be related to the topology change of the Fermi surfaces. [ABSTRACT FROM AUTHOR]

We have investigated the magnetic properties in the well localized compound NdFe2Al10 and the Kondo semiconductor Cer2Al10 (T = Ru, Os) to clarify the origin of the unusual magnetic order in Cer2Al10. In NdFe2Al10, the experimental results of the magnetic properties could be reproduced very well by the mean-field calculation for the two-sublattice model. In CeT2Al10 we could reproduce the anisotropic magnetic susceptibility in the paramagnetic region above 60-100 K very well by the mean-field calculation for the two-sublattice model introducing an anisotropic exchange interaction and the recently determined crystalline electric field (CEF) level scheme from Strigari et al. [Phys. Rev. B 86, 081105 (2012)]. However, in the antiferromagnetic (AFM) ordered state, we could not reproduce the experimental results at all in the framework of the mean-field calculation for the two-sublattice model. We propose that although the magnetic properties in the paramagnetic region above 60-100 K could be understood well by a localized picture, the ordered state could not, and that the c-f hybridization, especially along the a axis, is associated with the unusual magnetic order in CeT2Al10. [ABSTRACT FROM AUTHOR]

The ternary intermetallic compound TbPdAl crystallizes in the hexagonal ZrNiAl-type and the orthorhombic TiNiSi-type structures. The former compound undergoes two successive antiferromagnetic transitions with the Ne¨el temperatures of TN1=43 K and TN2=22 K. It is also characteristic that this compound exhibits an isostructural phase transition at around T=100 K. In this work, to investigate the origin of this transition, we have carried out extended X-ray absorption fine structures (EXAFS) and X-ray absorption near edge structure (XANES) measurements at the Tb L3- and Pd K-edge. It was found that Fourier transforms for k3-weighted Tb L3-edge EXAFS spectra changed below and above the transition temperature, which is consistent with the existence of the structural transition. In addition, slight temperature dependence was observed in the Pd K-edge XANES spectra, whereas the spectra at the Tb L3-edge showed no obvious change. This result suggests that the transition is caused mainly by the change of the electronic structure of Pd. [Copyright &y& Elsevier]