• Fadley, C. S.
• Braun, J.
• Kobayashi, K.
• Ouyang, L.
• Bordel, C.
• Ebert, H.
• Yamashita, Y.
• Gray, A. X.
• Minár, J.
• Ueda, S.
• Smith, D. J.
• Hellman, F.

Abstract

<p>The structural and electronic properties of epitaxial and amorphous Fe _xSi_1-x alloys with x = 0.72 and 0.67 near the binary Heusler composition of x = 0.75 were determined using hard x-ray photoelectron spectroscopy (HXPS). By performing the measurements at a photon energy of 5950.3 eV, the bulk-sensitivity of the measurement is enhanced by a factor of 4-7 compared to conventional soft x-ray photoelectron spectroscopy at about 1000 keV. HXPS probes, on average, as far as 76 Å into the Fe _xSi_1-x samples. Via core-level spectra, it is found in the amorphous alloy that, in spite of the disordered structure that could lead to a broad distribution of chemical environments, the Si environment is mostly unique. Valence-band spectra reveal a clear distinction between the contributions of the two inequivalent Fe sites of the most highly ordered (x = 0.72, D0₃) epitaxial sample. The valence-band spectra are compared to results of fully relativistic coherent potential approximation calculations performed in the framework of the one-step model of photoemission, which reveal details of the atomic-orbital makeup of various features, and generally exhibit good agreement with experiment.</p>

Topics

• impedance spectroscopy
• amorphous
• experiment
• x-ray photoelectron spectroscopy