Pressure-induced transitions in R Co5(R= Y, La) studied by x-ray emission spectroscopy, x-ray diffraction and density functional theory

Hitoshi Yamaoka; Eike F Schwier; Yoshiya Yamamoto; Takuma Kawai; Naohito Tsujii; Naohisa Hirao; Nozomu Hiraoka; Hirofumi Ishii; Jun'ichiro Mizuki

doi:10.1088/1361-648X/ac62a5

Pressure-induced transitions in R Co₅(R= Y, La) studied by x-ray emission spectroscopy, x-ray diffraction and density functional theory

J Phys Condens Matter. 2022 Apr 20;34(25). doi: 10.1088/1361-648X/ac62a5.

Authors

Hitoshi Yamaoka¹, Eike F Schwier², Yoshiya Yamamoto³, Takuma Kawai³, Naohito Tsujii⁴, Naohisa Hirao⁵, Nozomu Hiraoka⁶, Hirofumi Ishii⁶, Jun'ichiro Mizuki³

Affiliations

¹ RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan.
² Institute of Physics, Experimental Physics VII, University of Würzburg, Am Hubland 97074, Würzburg, Germany.
³ Graduate School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan.
⁴ International Center for Materials Nanoarchitechtonics, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan.
⁵ Japan Synchrotron Radiation Research Institute, Sayo, Hyogo, 679-5198, Japan.
⁶ National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan, Republic of China.

PMID: 35354125
DOI: 10.1088/1361-648X/ac62a5

Abstract

The hydrostatic pressure dependent evolution of the electronic and magnetic structure of LaCo₅and YCo₅was investigated by means of x-ray emission spectroscopy, x-ray diffraction, and spin-polarized density functional theory (DFT) calculations. Using experimental lattice parameters the DFT correctly predicts the pressure of the magnetic transition in both compounds to be 26 GPa (La) and 22-23 GPa (Y). The transition was experimentally resolved in the changes of the electronic structure via the integrated absolute difference of the CoKβemission spectra. Comparison of theory and experiment confirm for the first time a common feature in both LaCo₅and YCo₅to be the source of the transition; the Fermi-level crossing of an up-spin polarized flat band driving the systems into a low spin configuration via a Lifshitz type transition of the Fermi surface. Another phase transition observed around 12 GPa in LaCo₅was clarified to be caused by the change in the down-spin density of states at the Fermi level.

Keywords: DFT calculation; RCo5; high pressure; phase transition; x-ray emission spectroscopy.