Bulk electronic structure of non-centrosymmetric EuTGe3 (T= Co, Ni, Rh, Ir) studied by hard x-ray photoelectron spectroscopy

Abstract

Non-centrosymmetric EuTGe3 (T=Co, Ni, Rh, and Ir) possesses magnetic Eu2+ ions and antiferromagnetic ordering appears at low temperatures. Transition metal substitution leads to changes of the unit cell volume and of the magnetic ordering. However, the magnetic ordering temperature does not scale with the volume change and the Eu valence is expected to remain divalent. Here we study the bulk electronic structure of non-centrosymmetric EuTGe3 (T=Co, Ni, Rh, and Ir) by hard x-ray photoelectron spectroscopy. The Eu 3d core level spectrum confirms the robust Eu2+ valence state against the transition metal substitution with a small contribution from Eu3+. The estimated Eu mean-valence is around 2.1 in these compounds as confirmed by multiplet calculations. In contrast, the Ge 2p spectrum shifts to higher binding energy upon changing the transition metal from 3d to 4d to 5d elements, hinting of a change in the Ge-T bonding strength. The valence bands of the different compounds are found to be well reproduced by ab initio band structure calculations.

References in corpus (4)

• Heavy Fermions and Quantum Phase Transitions
• The Galaxies Beamline at SOLEIL Synchrotron: Inelastic X-ray Scattering and Photoelectron Spectroscopy in the Hard X-ray Range
• Magnetic properties and complex magnetic phase diagram in non centrosymmetric EuRhGe${}_3$ and EuIrGe${}_3$ single crystals
• Valence fuctuation and magnetic ordering in EuNi2(P1-xGex)2 single crystals

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• Synchrotron x-ray diffraction and DFT study of non-centrosymmetric EuRhGe3 under high pressure
• Helicity Selection of the Cycloidal Order in Noncentrosymmetric EuIrGe${}_3$