Magnetic twisted state of Fe/Tb multilayers

The information of the Fe and Tb magnetic moments in [Fe(12 nm)/Tb(15 nm)](25) multilayer was got separately with X-ray magnetic circular dichroism (XMCD) measurements at various temperature. The Tb magnetic moments become to twist with increasing the applied magnetic field, as follows. (1) When the applied field H is less than the coercive force H-C, Fe and Tb magnetic moments align anti-parallel, Fe moments being parallel to the magnetic field. This would be due to the ordinary exchange coupling between Fe and Tb magnetic moments. (2) H > H-C, a twisted magnetic structure appears when the sample temperature is low, particularly lower than 150 K. This magnetic phase could come from the competition among the exchange coupling, the Zeeman energy and the anisotropic energy. (C) 2004 Elsevier Ltd. All rights reserved.