Simultaneous magnetic and chemical imaging of Nd-Fe-B thin films by means of XMCD-PEEM technique

The coercivity mechanism of Nd-Fe-B thin film samples with and without Nd deposition was investigated by simultaneous chemical and magnetic imaging by means of X-ray magnetic circular dichroism-photoemission electron microscopy. The two Nd-Fe-B thin film samples exhibited almost the same surface morphology and magnetic domain patterns, but their coercive fields were quite different, being 0.98 T for the sample with Nd deposition and 0.55 T for sample without Nd deposition. The chemical distribution of Nd revealed that Nd aggregates with the average size of 130 nm exist, and the density in the Nd-deposited sample is much higher than that in the not deposited one. A comparison of the magnetic and chemical contrast images implied that the Nd aggregates act as domain wall pinning sites, indicating that the large coercivity difference in the Nd-Fe-B thin films would be attributable to the different density of wall pinning sites.  

This work was partially supported by the Elements Strategy Initiative Center for Magnetic Materials fromMEXT, the Management Expenses Grants for National Universities Corporations from MEXT, and JSPSKAKENHI Grant Number 24360261. The XMCD measurements were performed with the approval of theJapan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2014B1272)