title: Self-Injection Locking of a Vortex Spin Torque Oscillator by Delayed Feedback.
abstract: The self-synchronization of spin torque oscillators is investigated experimentally by re-injecting its radiofrequency (rf) current after a certain delay time. We demonstrate that the integrated power and spectral linewidth are improved for optimal delays. Moreover by varying the phase difference between the emitted power and the re-injected one, we find a clear oscillatory dependence on the phase difference with a 2π periodicity of the frequency of the oscillator as well as its power and linewidth. Such periodical behavior within the self-injection regime is well described by the general model of nonlinear auto-oscillators including not only a delayed rf current but also all spin torque forces responsible for the self-synchronization. Our results reveal new approaches for controlling the non-autonomous dynamics of spin torque oscillators, a key issue for rf spintronics applications as well as for the development of neuro-inspired spin-torque oscillators based devices.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Japan.|Unité Mixte de Physique, CNRS, Thales, Unive. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: Sumito
authors.initials: S
authors.lastname: Tsunegi
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Unive. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: Eva
authors.initials: E
authors.lastname: Grimaldi
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Unive. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Lebrun
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kubota
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Unive. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: Alex S
authors.initials: AS
authors.lastname: Jenkins
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Japan.
authors.forename: Kay
authors.initials: K
authors.lastname: Yakushiji
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Fukushima
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Unive. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: Paolo
authors.initials: P
authors.lastname: Bortolotti
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Unive. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Grollier
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Yuasa
authors.affiliation: Unité Mixte de Physique, CNRS, Thales, Unive. Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Cros