Near-Curie magnetic anomaly at the Ni/C interface observed by electron holography |
| |
Authors: | Loris Ferrari Marvin A Schofield Yimei Zhu |
| |
Institution: | a Department of Physics, University of Bologna, V.le B. Pichat 6/2, 40127 Bologna, Italy b Brookhaven National Laboratory, Building 480, Upton, NY 11973, USA |
| |
Abstract: | We analyze with electron holography carried out in a transmission electron microscope the near-Curie behavior of magnetism at the edge of a Nickel thin film coated with Carbon. In-situ experiments with finely controlled variations of the sample temperature reveal an anomaly in the ferromagnetic to paramagnetic phase transition when the film temperature is a few degrees above the nominal Curie point. We interpret the anomaly as a strain-induced spin reorientation transition triggered by the differential thermal expansion of Carbon and Nickel. We present a model that quantitatively reproduces the main features of the observed signal. The model is developed in terms of an anisotropic, temperature dependent exchange coupling between the Nickel moments at the Carbon interface that favors their vertical alignment at low temperatures. |
| |
Keywords: | Electron holography Curie temperature Nickel film Surface anisotropy Spin-reorientation transition |
本文献已被 ScienceDirect 等数据库收录! |