Magnetic energies of single submicron permalloy rectangles determined via magnetotransport

Abstract

We have investigated the magnetic properties of single submicron permalloy rectangles with a thickness of 20 nm and an aspect ratio of 2:1 via anisotropic magnetoresistance (AMR). Preparation and investigation via magnetotransport are performed in situ in ultrahigh vacuum. The field-dependent magnetization behavior of the two generic cases with the magnetic field applied perpendicular and parallel to the long axis of the rectangles is studied. Due to the high sensitivity of our setup, single field sweeps are sufficient to obtain magnetoresistance curves of structures with dimensions as small as $600\ifmmode\times\else\texttimes\fi{}300\text{ }{\text{nm}}^{2}$. To link features of the AMR to changes in the micromagnetic states, the remanent state has been investigated via scanning electron microscopy with polarization analysis. Our main result is that the energy density of micromagnetic states can be obtained from the hard-axis magnetization behavior. It is demonstrated that a C/S state can be distinguished from a Landau state and the energy difference between both states is determined.