Measuring lateral magnetic structures in thin films using time-of-flight polarized neutron reflectometry

Abstract

Polarized neutron reflectometry (PNR) has recently been applied to study lateral magnetic structures such as regular micron-sized magnetic arrays on a surface. To date, however, there is a lack of detailed accounts of the features observed in the scattered intensity map in the special case of time-of-flight (TOF) PNR. We present here preliminary measurement results on lithographically produced arrays of micron-sized rectangular permalloy magnetic bars. The measurements demonstrate the potential of the method to provide detailed structural information on a laterally patterned sample, as well as on its magnetic characteristics. The information can be obtained by analyzing the specular reflection along with three off-specular Bragg sheets. Most of the features seen experimentally can be interpreted by using simple heuristic arguments. In addition, we also present results of a study of lateral magnetic domains in an exchange-biased Co/CoO bilayer film to illustrate the capability of TOF PNR in the study of large lateral magnetic domains in the case when almost no off-specular scattering is detected.