Structural and electronic investigation of TbPdAl by means of EXAFS and XANES measurements

Abstract

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 Nëel temperatures of TN1=43K and TN2=22K. It is also characteristic that this compound exhibits an isostructural phase transition at around T=100K. 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.