Effect of CoSi2 interfacial layer on the magnetic properties of Si vertical bar CoSi2 vertical bar Sm-Co thin films

Abstract

Magnetic thin films with a layer sequence of Si vertical bar CoSi2 vertical bar Sm-Co were grown by direct sputter deposition at elevated temperatures, through interfacial diffusion between Si (1 0 0) substrate and the overlying Sm-Co layer. HR-TEM analysis revealed the occurrence of CoSi2 -interfacial layer close to the Si-substrate surface, with controllable thicknesses of similar to 20 and 35 nm at deposition temperatures: 450 and 500 degrees C, respectively. XRD studies confirmed the crystallization of Sm2Co17 and SmCo5 magnetic phases accompanied by the other phases such as CoSi2 and SmCoSi2 due to the intermixing of Co and Si-atoms at higher deposition temperatures. The measured coercivity values are found to be increased from 8.7 to 11.6 kOe at higher CoSi2-layer thickness. The angular-dependent hysteresis measurements demonstrated a distinct isotropic and uniaxial magnetic anisotropy characteristics for the Sm-Co films consisting of 35 and 20-nm thick CoSi2 interfacial layers, respectively and the associated magnetization reversal mechanisms are discussed using the Stoner-Wohlfarth model. The temperature coefficients of remanence (alpha) and coercivity (beta) were determined from the temperature-dependent hysteresis curves. The Sm-Co films consisting of 35-nm thick CoSi2-layer exhibited a better thermal stability with 'alpha' and 'beta' values of 0.35 +/- 0.05%/degrees C and -0.13 +/- 0.02%/degrees C, respectively. The results of present study provide splendid opportunities for exploiting the potential of CoSi2 as an under layer, for growing the Sm-Co films towards high-temperature applications