Magnetoresistance oscillations induced by periodically arranged micromagnets

Abstract

Probing magnetic fields can be done, e.g., by employing the well established Hall effect. Alternatively, we make use of the ballistic motion of electrons in high mobility two-dimensional electron systems (2DES) to probe electrically the stray field of periodically arranged micomagnets. We investigate the magnetoresistance of the 2DES underneath arrays of magnetic strips and magnetic dots having periods between 500 nm and 1 µm. The periodic stray field gives rise to pronounced oscillations of the resistivity as a function of a homogeneous (weak) magnetic field. The magnetization orientation of the dots and strips can be aligned in different directions with respect to the current flow through the device. The observed magnetoresistance depends characteristically on the magnetization direction and can be understood in terms of the stray field pattern probed by the electrons.