Abstract
We have investigated the effects of atomic disorder on the electronic structure and some physical properties of Heusler alloy (HA) films. Flash evaporation onto glass substrates at different temperatures (from 150 to 750 K) and postannealing at various temperatures were employed to manipulate the structural order in HA films. The -ordered HA films exhibit the magnetic, the transport, and the optical properties close to those of the bulk ordered sample. Increase in the structural disorder ( state) causes the reduction in the saturation magnetization and the Curie temperature down to the paramagnetic state for amorphous films. The recrystallization of amorphous HA films is accompanied by an increase in resistivity by about 10%, which is interpreted to be related to the energy gap formation at the Fermi level for the minority bands in the -ordered state of HA. The energy-band structures of -ordered HA have been calculated by using an all-electron full-potential linearized-augmented-plane-wave method. The optical and the magneto-optical properties of -ordered HA have been experimentally investigated and explained in terms of the band structures. It was experimentally shown that the optical properties of crystalline (or )-type ordered alloy at a temperature much higher than do not significantly change. Structural disorder in HA from the crystalline to the amorphous state also does not radically alter the states responsible for the interband-absorption-peak formation.
3 More- Received 6 October 2007
DOI:https://doi.org/10.1103/PhysRevB.77.195104
©2008 American Physical Society