| AVS 59th Annual International Symposium and Exhibition | |
| Magnetic Interfaces and Nanostructures | Wednesday Sessions |
| Session MI+OX-WeA |
| Session: | Spintronics, Magnetoelectrics, Multiferroics |
| Presenter: | C. Baldasseroni, Univ. of California Berkeley |
| Authors: | C. Baldasseroni, Univ. of California Berkeley C. Bordel, Univ. of California Berkeley A.X. Gray, SLAC National Accelerator Lab A.M. Kaiser, Peter-Grünberg-Institut, Germany F. Kronast, Helmholtz-Zentrum Berlin für Materialien und Energie, Germany J. Herrero-Albillos, Centro Univ. de la Defensa, Spain C.M. Schneider, Peter-Grünberg-Institut, Germany C.S. Fadley, Lawrence Berkeley National Lab F. Hellman, Univ. of California Berkeley |
| Correspondent: | Click to Email |
Equiatomic FeRh is a unique material that undergoes a first order antiferromagnetic (AF) to ferromagnetic (FM) transition just above room temperature (near 350 K). This phase transition can be driven by temperature or magnetic field and is coupled to a lattice expansion. Current investigations of this unique transition range from the fundamental understanding of the origin and nature of the transition to applications associated with the transition such as a giant magnetocaloric effect.
FeRh has been studied in the bulk for over 50 years and most recently in thin film form, where the transition temperature has been shown to be sensitive to changes in composition and substrate-induced strain as well as structural and chemical order. FeRh thin films are also a promising candidate for heat-assisted magnetic recording in an exchange-spring system with a hard magnetic layer (for example FePt). Understanding the magnetic domain structure of FeRh and the mechanisms of the transition at the microscopic level involving nucleation and growth of magnetic domains as a function of temperature is vital for its further application to magnetic storage technology. Although many experimental studies of the transition have been recently performed on FeRh thin films, most of them focus on macroscopic measurements. Only a few studies have attempted at imaging domains through the transition but these have been limited to magnetic force microscopy (MFM) on bulk samples and were limited by lack of temperature control which prevented a study of the nucleation and growth across the full transition.
We used x-ray magnetic circular dichroism and photoemission electron microscopy to study the evolution of ferromagnetic domains across the temperature-driven AF to FM phase transition in uncapped and capped epitaxial FeRh thin films. The coexistence of the AF and FM phases was evidenced across the broad transition and the different stages of nucleation, growth and coalescence were observed. We also found that the FM phase nucleates into single domain islands and the width of the transition of the individual nuclei is sharper than that of the macroscopic transition.