Article abstract
Nature Physics 3, 492 - 497 (2007)
Published online: 7 May 2007 | doi:10.1038/nphys618
Subject Categories: Electronics, photonics and device physics | Nanotechnology | Techniques and instrumentation
Shaped angular dependence of the spin-transfer torque and microwave generation without magnetic field
O. Boulle1,
V. Cros1,
J. Grollier1,
L. G. Pereira1,
C. Deranlot1,
F. Petroff1,
G. Faini2,
J. Barna
3
&
A. Fert1
Abstract
The generation of oscillations in the microwave frequency range is one of the most important applications expected from spintronics devices exploiting the spin-transfer phenomenon, which is the reorientation of the magnetization of a ferromagnetic domain by spin-polarized current. Here we report transport and microwave power measurements on specially designed nanopillars, for which a non-standard angular dependence of the spin-transfer torque is predicted by theoretical models. We observe a new kind of current-induced dynamics that is characterized by large angle precessions in the absence of any applied field. This is also predicted by simulations including a 'wavy' angular dependence of the torque. This type of nanopillar, which is able to generate microwave oscillations in zero applied magnetic field, could represent an interesting method for the implementation of spin-transfer oscillators. We also emphasize the theoretical implications of our results on the angular dependence of the torque.
- Unité Mixte de Physique CNRS/Thales and Université Paris Sud XI, Route départementale 128, 91767 Palaiseau, France
- Laboratoire de Photonique et de Nanostructures LPN-CNRS, Route de Nozay, 91460 Marcoussis, France
-
Department of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Pozna
, Poland
Correspondence to: V. Cros1 e-mail: vincent.cros@thalesgroup.com
Correspondence to: L. G. Pereira1 Present address: Instituto de Física, UFRGS, 91501-970 Porto Alegre, RS, Brazil
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