Evolution of valence-specific spin states and local distortions in La${}_{2-x}$Sr${}_x$CoO${}_4$

Abstract

We present X-ray spectroscopic evidence for the evolution of valence-specific spin states and tetragonal distortions in single-layer cobaltates. Measurements of Co $L_3$-edge resonant inelastic X-ray scattering reveal the $t_{2g}$ electronic structure of Co for hole-doped La${}_{2-x}$Sr${}_x$CoO${}_4$ ($x$ = 0.5, 0.7 and 0.8). As the Sr-doping $x$ increases, the tetragonal splitting of the $t_{2g}$ states of high-spin Co${}^{2+}$ decreases, whereas that of low-spin Co${}^{3+}$ increases and the fraction of high-spin Co${}^{3+}$ increases. The results enable us to clarify the origin of the change of magnetic anisotropy and in-plane resistivity in a mixed-valence cobaltate caused by the interplay of spin-orbit coupling and tetragonal distortion.

8 pages, 6 figures. published in Phys. Rev. B online 12 August 2021

References in corpus (9)

• The spin state transition in LaCoO${}_3$; revising a revision
• Controlling orbital moment and spin orientation in CoO layers by strain
• Spin blockade, orbital occupation and charge ordering in La_(1.5)Sr_(0.5)CoO4
• Magnetic correlations in La2-xSrxCoO4 studied by neutron scattering : possible evidence for stripe phases
• Hour-glass magnetic spectrum in an insulating, hole-doped antiferromagnet
• Coulomb correlations intertwined with spin and orbital excitations in LaCoO${}_3$
• Hour-glass magnetic excitations induced by nanoscopic phase separation in cobalt oxides La${}_{2-x}$Sr${}_x$CoO${}_4$
• Anisotropic Susceptibility of La_2-xSr_xCoO_4 related to the Spin States of Cobalt
• Evidence for a temperature-induced spin-state transition of Co3+ in La2-xSrxCoO4