Pressure evolution of electronic and crystal structure of noncentrosymmetric EuCoGe3

We report on the pressure evolution of the electronic and crystal structures of the noncentrosymmetric antiferromagnet EuCoGe3. Using a diamond anvil cell, we performed high pressure fluorescence detected near-edge x-ray absorption spectroscopy at the Eu L3, Co K, and Ge K edges and synchrotron powder x-ray diffraction. In the Eu L3 spectrum, both divalent and trivalent Eu peaks are observed from the lowest pressure measurement (similar to 2 GPa). By increasing pressure, the relative intensity of the trivalent Eu peak increases, and an average Eu valence continuously increases from 2.2 at 2 GPa to 2.31 at similar to 50 GPa. On the other hand, no discernible changes are observed in the Co K and Ge K spectra as a function of pressure. With the increase in pressure, lattice parameters continuously decrease without changing I4mm symmetry. Our study revealed a robust divalent Eu state and an unchanged crystal symmetry of EuCoGe3 against pressure.

Automated summary

We investigated the pressure effects on the electronic and crystal structures of EuCoGe3, a noncentrosymmetric antiferromagnet. By performing high-pressure fluorescence detected near-edge x-ray absorption spectroscopy and synchrotron powder x-ray diffraction, we found that the valence state of Eu changes under pressure, while the Co and Ge spectra remain unchanged. The lattice parameters of EuCoGe3 decrease with increasing pressure, but the crystal symmetry remains unchanged.