Influence of structural disorder on the magnetic, optical, and transport properties of beta-phase Co0.50Ti0.50 alloy films

The influence of the structural disorder on the magnetic, optical, and tran sport properties of the Co0.50Ti0.50 alloy films has been investigated. The disordered state in the alloy films was obtained by vapor-quenching deposi tion onto substrates cooled by liquid nitrogen. The transport properties of the ordered and disordered alloy films have been measured in a temperature range of 4.2-300 K. The optical properties were measured by spectroscopic ellipsometry at 293 K in an energy range of 0.5-4.7 eV. The experimental op tical data of the ordered CoTi compound were compared with the results of a b initio calculations made by using the linearized-augmented plane-wave met hod with the local-density approximation, and explained in terms of the ele ctronic energy band structure. An excellent agreement between the experimen tal and calculated optical conductivity spectra of the ordered compound was achieved by the inclusion of the quasiparticle self-energy correction. It was shown that the disordered state in the Co0.50Ti0.50 alloy film is ferro magnetically ordered at 100 K. The changes in the electronic structure of t he Co0.50Ti0.50 alloy caused by the order-disorder structural transformatio n are explained on the analyses of the measured optical and resistivity dat a. [S0163-1829(99)00735-3].