Magnetotransport and domain wall pinning in high purity electromigrated nanocontacts
André Loescher (Inst. f. Physik)

Abstract: Magnetotransport measurements on magnetic nanocontacts have been performed with the aim to understand the interactions between spin-polarized charge carriers and magnetization on the nanoscale. Here we study the evolution of magnetoresistance (MR) in electromigrated ferromagnetic junctions, obtained in clean ultra-high vacuum (UHV) conditions. While previously nanocontacts with variable constriction width have been investigated, the fundamental behaviour of magnetization in such confined systems is not fully understood, with measurement artifacts arising from contamination, magnetostriction e.t.c., often complicating the interpretation of results. Controlled electromigration of notched half ring Permalloy (Ni80Fe20) structures was performed in order to tailor the size of the contact in-situ. The MR was measured as a function of the resistance level in order to study the magnetic properties and characterize the strength and extent of the domain wall pinning potential.