Domain structures in Fe100-xGax/MgO(001) films

Abstract

Resumen del trabajo presentado al 9th Joint European Magnetic Symposia (JEMS), celebrado en Mainz (Alemania) del 3 al 7 de septiembre de 2018.In this work we present the magnetic domain structures of Fe100-xGax/MgO(001)(x 16 a fine stripe-like structure is observed. The stripe phase is explained considering a perpendicular anisotropy Ku with a value comparable and lower than the shape anisotropy coefficient Ksh. Hysteresis loops performed along the film normal indicate that Ku/Ksh is around 0.4 (x > 16), a value for which the observation of the stripe phase is expected. The magnetoelastic (ME) anisotropy energy term favors in-plane magnetization due to the signs of residual strain and ME stress coefficient. The presence of next-nearest-neighbor Ga pairs in Fe100-xGax alloys has been addressed as source for the cubic anisotropy constant K1 while in epitaxial films a preferential asymmetry in the formation of these Ga-Ga pairs, along the out-of-plane direction, can result in large Ku and explain the stripe structure observed for x > 16. It appears that small variations of the Ga-Ga pair distribution in a body, although undetected by local probes techniques, such as EXAFS, could introduce strong magnetic anisotropy in that specimen.Peer Reviewe