title: Giant thermal spin-torque-assisted magnetic tunnel junction switching.
abstract: Spin-polarized charge currents induce magnetic tunnel junction (MTJ) switching by virtue of spin-transfer torque (STT). Recently, by taking advantage of the spin-dependent thermoelectric properties of magnetic materials, novel means of generating spin currents from temperature gradients, and their associated thermal-spin torques (TSTs), have been proposed, but so far these TSTs have not been large enough to influence MTJ switching. Here we demonstrate significant TSTs in MTJs by generating large temperature gradients across ultrathin MgO tunnel barriers that considerably affect the switching fields of the MTJ. We attribute the origin of the TST to an asymmetry of the tunneling conductance across the zero-bias voltage of the MTJ. Remarkably, we estimate through magneto-Seebeck voltage measurements that the charge currents that would be generated due to the temperature gradient would give rise to STT that is a thousand times too small to account for the changes in switching fields that we observe.
authors.affiliation: IBM Almaden Research Center, San Jose, CA 95120; apushp@us.ibm.com stuart.parkin@mpi-halle.mpg.de.
authors.forename: Aakash
authors.initials: A
authors.lastname: Pushp
authors.affiliation: IBM Almaden Research Center, San Jose, CA 95120; Department of Electrical Engineering, Stanford University, Stanford, CA 94305; and.
authors.forename: Timothy
authors.initials: T
authors.lastname: Phung
authors.affiliation: IBM Almaden Research Center, San Jose, CA 95120;
authors.forename: Charles
authors.initials: C
authors.lastname: Rettner
authors.affiliation: IBM Almaden Research Center, San Jose, CA 95120;
authors.forename: Brian P
authors.initials: BP
authors.lastname: Hughes
authors.affiliation: IBM Almaden Research Center, San Jose, CA 95120;
authors.forename: See-Hun
authors.initials: SH
authors.lastname: Yang
authors.affiliation: IBM Almaden Research Center, San Jose, CA 95120; Max Planck Institute for Microstructure Physics, Halle (Saale), D-06120, Germany apushp@us.ibm.com stuart.parkin@mpi-halle.mpg.de.
authors.forename: Stuart S P
authors.initials: SS
authors.lastname: Parkin
keywords: MRAM; spin caloritronics; spintronics