The band structure of chemically ordered

Abstract

Owing to surface diffusion, the molecular beam epitaxy (MBE) technique has made it possible to produce new binary alloy films by coevaporation on a single-crystal substrate in an ultrahigh vacuum. In this fashion, a hexagonal close-packed (hcp) structure of the Co 3 Pt compound with ferromagnetic and chemical order has been discovered recently which was not previously known in the bulk alloy equilibrium phase diagram. Using a tight-binding linear muffin-tin orbital (TB-LMTO) method for the electronic structure of Co 3 Pt, we treat first the reference case of the fcc L1 2 phase and then the hcp phase. In this last phase we consider both the standard DO 19 structure and a modified version of it. We perform the band-structure calculation in both the paramagnetic and ferromagnetic cases, and on the basis of a total energy calculation we arrive at the conclusion that the ferromagnetic phase of the DO 19 structure is the most stable.

Giant enhancement of magneto-optical response and increase in perpendicular magnetic anisotropy of ultrathin Co/Pt(111) films upon thermal annealing

“…The angle-integrated UP spectrum of the as-grown film and those for different annealing temperatures in a difference form are compiled in Fig. The calculated electronic structure near the Fermi edge by a tight-binding linear muffin-tin orbital method, 25 and the experimental results reflected by the new peaks in the magneto-optical Kerr spectra of the ordered Co 3 Pt alloy with a hexagonal stacking during annealing around 650 K, 1 are similar to our results. The spectrum of the as-grown 1.0 ML Co/Pt͑111͒ ultrathin film is characterized by a sharp Fermi edge and a peak P1 located at 4.5 eV below the Fermi level, which arises from the d-band emission.…”

Band theory of induced magnetic moments in CoM(M=Rh, Ru) alloys

“…This structure we call modified DO 19 or DO 19 Ј Besides hcp structure these alloys may also exist in a cubic structure L1 2 where three simple cubic sublattices of a face centred cube are occupied by Co and the remaining one is occupied by M . 8,9 According to phase diagram Co 3 Ru does not exist in the L1 2 phase. 10 Hence, for Co 3 Ru the energy band calculations have been done only for hcp structure.…”

“…These points are found sufficient to obtain a converged result for these structures. 9 Since the lattice parameters for these alloys are not yet known precisely, we have performed the calculations of the electronic structure in each case as a function of the lattice parameter to obtain the lowest energy lattice constant. For a given alloy structure this lowest energy lattice parameter is found to be the same in para ( P) and ferro (F)-magnetic phases.…”

Effect of Co doping on catalytic activity of small Pt clusters

“…27 Several first principles ab initio calculations of the electronic structures of Pt-Co alloy systems have been reported. [28][29][30][31] Kootte et al 31 performed spin-polarized band structure calculations of Co x Pt 1−x alloys with x = 0, 0.25, 0.5, 0.75, and 1, and reported density of states and magnetic moments of the clusters. Lee et al 32 investigated the electronic structure of bulk Pt-Co alloys using x-ray spectroscopy and DFT calculations.…”