Magnetic stability of ultrathin FeRh films

This paper presents magnetic properties of highly ordered ultrathin FeRh films deposited on Si/SiO wafers with MgO as a buffer layer. The antiferromagnetic to ferromagnetic (FM) transitionis observed with a thickness as low as 3 nm. However, as the thickness decreases, the residual magnetization (Mrs) at low temperature increases and the amplitude of the transition decreases. In addition, the transition becomes much broader for the thinner films. This broadening is related to the grain size reduction in the thinner films. The temperature dependence of the magnetization of a highly ordered B2 FeRh film with a thickness of 10 nm was carefullymeasured as a function of field. The results show that the transition temperature decreases almost linearly with a rate of 0.93 K/kOe (heating) and 0.97 K/kOe (cooling) close to the value for the bulk samples, while Mrs obtained at 100 K increases rapidly at low field and then linearly at a field larger than 10 kOe, which clearly demonstrates that an applied field would induce FMstabilization in ultrathin FeRh films.