X-RAY CIRCULAR MAGNETIC DICHROISM (XCMD) AS A PROBE OF THE DYNAMICS OF THE SPIN REORIENTATION TRANSITIONS IN ND2FE14B AND ER2FE14B SYSTEMS

We present the first experimental observation of a spin reorientation phase transition (SRT) with the X-ray circular-magnetic-dichroism (XCMD) technique. The XCMD signal, related to the projection of the rare-earth moment on the direction of the X-ray beam, has been measured as a function of temperature for both, a first-order SRT in Er2Fe14B (abrupt reorientation by 90-degrees) and a second-order one in Nd2Fe14B (continuous tilt of the magnetization from the c-axis). The feasibility of this technique to study SRTs and the capability to better understand the magnetic behaviour of intermetallic compounds exhibiting coexistence of itinerant and localized magnetism are demonstrated.