Indication of exchange interaction induced spin splitting in unoccupied electronic states of the high- TC ferromagnet (Cr0.35Sb0.65)2Te3

We study the high Curie temperature ferromagnet (Cr0.35Sb0.65)2Te3 (TC=192K), using T-dependent x-ray absorption spectroscopy (XAS), x-ray magnetic circular dichroism (XMCD), and angle-resolved photoemission spectroscopy (ARPES). The T-dependent (25-220 K) XAS-XMCD evolution of Cr3d and Te5p unoccupied site- and orbital-projected states shows a systematic modification, which we interpret as due to spin-splitting below TC. The T-dependent XMCD intensity and leading-edge spin-sensitive shifts γexpt(T) follow bulk magnetization. ARPES measurements with hν=78eV show a metallic state with Sb 5p band dispersions at and near Fermi level (EF), consistent with bulk band-structure calculations for (Cr0.33Sb0.67)2Te3. However, surface-sensitive ARPES with hν=8.4eV above and below TC show linear band dispersions just below EF, suggesting a remnant of Dirac-type dispersions. Assuming the linear dispersion survives above EF, it implies a topologically trivial ferromagnet as the estimated Dirac point energy lies above the largest γexpt(T=25K). The Cr3d XAS-XMCD spectra can be simulated by charge transfer multiplet cluster model calculations with an exchange field Hex which quantitatively reproduces the experimental XMCD. At T=25K, the required exchange field Hex of ∼48T corresponds to a Zeeman energy ζ=2.8meV<TC=192K (= 16.5 meV) ≪γexpt∼140meV. The results indicate the role of Cr3d exchange interactions in causing spin-sensitive shifts in Cr3d states, and inducing comparable spin-sensitive shifts via hybridization in Te5p states of (Cr0.35Sb0.65)2Te3.