Unconventional GMR angular dependence using a compensated ferrimagnet

Abstract

International audienceWe have designed a GdCo/Cu/NiFe giant magnetoresistance (GMR) trilayer , the magnetoresistance of which does not always depend on the angle between the magnetisations of the electrodes. Using a GdCo ferrimagnetic alloy close to compensation, it was possible to experimentally reach the spin flop field B(sf) of the ferrimagnetic layer . Below B(sf), the ferrimagnetic layer behaves as a ferromagnetic layer , however above B(sf), the ferrimagnetic sublattice magnetisations are no longer antiparallel and rotate 90 degrees away from the GdCo layer totalmagnetisation, i.e. 90 degrees away from the applied field . the GMR responds to the angle between Co and NiFe magnetisations and not to the angle between GdCo and NiFe magnetisations. Such a structure allows to study the change of sign of the GdCo spin polarisation as a function of temperature, and details of the GdCo magnetisation when usual magnetometry is difficult. FeNi can be seen as a sensor for the in-plane component of Co sublattice magnetisation, whereas extraordinary Hall effect measurements give a complementary image of the perpendicular component of the Comagnetisation

Ferrimagnetic–ferromagnetic phase transition in Mn4N films favored by non-magnetic In doping

“…In this work, we demonstrated the formation of ferromagnetic Mn 4−x In x N from ferrimagnetic Mn 4 N just by doping non-magnetic In atoms. Considering that not only the magnetic phase of Mn 4 N but also its coercivity can be controlled by In doping while keeping the PMA, Mn 4 N-based latticematched heterostructure devices with Mn 4−x In x N layers acting as pinned-layers are promising like in GdCo/Cu/NiFe ferrimagnet/non-magnet/ferromagnet trilayers [55]. Perpendicular magnetic recording reported in [56] is also interesting, wherein a continuous multilayer structure and a granular layer consisting of ferromagnetic and ferrimagnetic regions are used.…”