title: Termination layer compensated tunnelling magnetoresistance in ferrimagnetic Heusler compounds with high perpendicular magnetic anisotropy.
abstract: Although high-tunnelling spin polarization has been observed in soft, ferromagnetic, and predicted for hard, ferrimagnetic Heusler materials, there has been no experimental observation to date of high-tunnelling magnetoresistance in the latter. Here we report the preparation of highly textured, polycrystalline Mn3Ge films on amorphous substrates, with very high magnetic anisotropy fields exceeding 7 T, making them technologically relevant. However, the small and negative tunnelling magnetoresistance that we find is attributed to predominant tunnelling from the lower moment Mn-Ge termination layers that are oppositely magnetized to the higher moment Mn-Mn layers. The net spin polarization of the current reflects the different proportions of the two distinct termination layers and their associated tunnelling matrix elements that result from inevitable atomic scale roughness. We show that by engineering the spin polarization of the two termination layers to be of the same sign, even though these layers are oppositely magnetized, high-tunnelling magnetoresistance is possible.
authors.affiliation: IBM Almaden Research Center, San Jose, California 95120, USA.
authors.forename: Jaewoo
authors.initials: J
authors.lastname: Jeong
authors.affiliation: IBM Almaden Research Center, San Jose, California 95120, USA.|Max-Planck Institute for Microstructure Physics, 06120 Halle (Saale), Germany.
authors.forename: Yari
authors.initials: Y
authors.lastname: Ferrante
authors.affiliation: IBM Almaden Research Center, San Jose, California 95120, USA.
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Faleev
authors.affiliation: IBM Almaden Research Center, San Jose, California 95120, USA.
authors.forename: Mahesh G
authors.initials: MG
authors.lastname: Samant
authors.affiliation: Max-Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Felser
authors.affiliation: IBM Almaden Research Center, San Jose, California 95120, USA.|Max-Planck Institute for Microstructure Physics, 06120 Halle (Saale), Germany.
authors.forename: Stuart S P
authors.initials: SS
authors.lastname: Parkin