Effects of the stoichiometry and chemical order on the electronic structure and magnetic properties of Cr-Pt alloys probed by angular-resolved photoemission

Abstract

The electronic structure of the intermetallic compound CrPt 3 is studied by angle-resolved ultraviolet photoemission spectroscopy on ͑001͒ and ͑111͒ surfaces of molecular-beam-epitaxy-grown epitaxial films in the photon energy range of 21-150 eV. The surface structures and the chemical order are investigated by reflecting high-energy electron diffraction. The partial density of states of CrPt 3 has been estimated using the photoionization dependence of the photoemission. The momentum dependence of the valence-band energies is determined for the ⌫-R bulk high-symmetry line and the ⌫-M and RϪX directions using synchrotron radiation. The nature of these bands was identified by a comparison with band-structure calculations based on densityfunctional theory in the local spin-density approximation. A good agreement between measured and ab initio calculated energy bands is found. Band mapping has also been performed using the angle-variation method on ͑001͒ surfaces excited by the He I emission line. For variations of the degree of surface order, a simple relationship between the electronic structure and magnetic properties of the alloy is found, which is discussed in terms of a modeled band structure. The magnetic anisotropy of this alloy is found to relate to the density of states at the Fermi level as determined by photoemission.

Theory for the Potential Shift for OH[sub ads] Formation on the Pt Skin on Pt[sub 3]Cr(111) in Acid

“…32 The authors concluded that the broad structure observed for the Pt 3 Cr DOS could be attributed to a mixing of Cr and Pt d-orbitals, and LSDA calculations corroborated this.…”

“…They found in the case of Pt 3 Cr that spin-unpolarized calculations failed to predict the L1 2 structures to be the most stable, in contradiction with the experimental observations. Many of the Cu 3 Au-type ordered alloys are magnetic, and it was found experimentally 24,[29][30][31][32][33][34] and theoretically [35][36][37][38][39] that the Pt 3 Cr-ordered alloy is ferrimagnetic, with the Cr-Cr pairs coupled ferromagnetically and the Cr-Pt pairs coupled antiferromagnetically. The magnetic moment is predominantly localized on Cr, and the opposite sign moment on the Pt site is very small.…”

Size effects of optical and magneto-optical properties of epitaxial CrPt3 films

“…The growth process and parameters are described in detail elsewhere. 17 Using a shutter, which covers different parts of the substrate, it was possible to obtain wedge-shaped samples with different CrPt 3 thicknesses. Other growth parameters, for example, substrate temperature or partial pressures of the constituents, were the same for each film thickness.…”

Glassy Phonon Heralds a Strain Glass State in a Shape Memory Alloy

“…Because Co is an impurity atom on the Ni sublattice, it is expected to form resonance (local) states. The formation of resonance electronic states from chemical disorder is an established concept[29], as is the connection between chemical disorder and electron band structure near the Fermi level[30]. Resonance states at the Fermi level will disrupt Fermi surface nesting because such localized states fill reciprocal space, including between nested Fermi surfaces.…”