Interfacial disorder and magnetic frustration in epitaxial Fe/Cr/Fe trilayers studied by thermoremanent magnetization

Abstract

Abstract. In order to investigate the relaxation phenomena in Fe/Cr(001) system with various degrees of interfacial magnetic frustration, we have epitaxially grown Fe/Cr/Fe(001) trilayers on MgO(001) substrate under several thermal conditions by using molecular beam epitaxy (MBE) technique, and measured the time dependence of the thermoremanent magnetization (TRM) in the absence of magnetic field after field cooling process from 300 K to a measuring temperature 250 K under a magnetic field of 100 Oe after a waiting time tw = 0 ∼ 100 min. The reflection high energy electron diffraction (RHEED) was employed for confirming the epitaxial growth and for evaluating degree of the interfacial flatness in each sample. From the experimental results, we found that 1) all the present epitaxially grown Fe/Cr/Fe(001) trilayers are ferromagnetic at 300 K, 2) the TRM shows the logarithmic time dependence with larger magnetic viscosity coefficient for the samples which have more disordered interface relative to the other samples, and 3) the most disordered sample shows clearly tw dependence as observed in spin glasses. These results indicate that the interfacial magnetic frustration in the epitaxial Fe/Cr(001) system increases with increasing the interfacial disorder.