Surface-induced resistivity of CoSi2 films and violations of Mathiessen's rule

Abstract

We analysed the residual resistivity data for more than 40 films of COSi2 reported by different groups using the available quantum theories of size effects in metal films. We found that the predictions of the model of Trivedi and Ashcroft (1988 Phys. Rev. B 38 12298) of Tesanovic et al (1986 Phys. Rev. Lett. 57 2760), and of the mSXW theory (Munoz et al 1999 J. Phys. Condens. Matter 11 L299) agree roughly with the data and with each other over the entire range of thickness 1 nm ≤ t ≤ 110 nm, although the rms roughness amplitude needed to best describe the residual resistivity data is somewhat different for each model. All three models predict surprisingly similar values for the film resistivity ρF and for the surface resistivity ρS arising from electron-surface scattering. All three models indicate that Mathiessen's rule is violated in thin CoSi2 films, that is, ρF ≠ ρS + ρB where ρB is the bulk resistivity. For 110 nm < t < 10 nm, the resistivity of the film exceeds by some 25-55% the