title: Understanding of Phase Noise Squeezing Under Fractional Synchronization of a Nonlinear Spin Transfer Vortex Oscillator.
abstract: We investigate experimentally the synchronization of vortex based spin transfer nano-oscillators to an external rf current whose frequency is at multiple integers, as well as at an integer fraction, of the oscillator frequency. Through a theoretical study of the locking mechanism, we highlight the crucial role of both the symmetries of the spin torques and the nonlinear properties of the oscillator in understanding the phase locking mechanism. In the locking regime, we report a phase noise reduction down to -90  dBc/Hz at 1 kHz offset frequency. Our demonstration that the phase noise of these nanoscale nonlinear oscillators can be tuned and eventually lessened, represents a key achievement for targeted radio frequency applications using spin torque devices.
authors.affiliation: Unité Mixte de Physique CNRS/Thales and Université Paris Sud, 1 Avenue Fresnel, 91767 Palaiseau, France.
authors.forename: R
authors.initials: R
authors.lastname: Lebrun
authors.affiliation: Unité Mixte de Physique CNRS/Thales and Université Paris Sud, 1 Avenue Fresnel, 91767 Palaiseau, France.
authors.forename: A
authors.initials: A
authors.lastname: Jenkins
authors.affiliation: Unité Mixte de Physique CNRS/Thales and Université Paris Sud, 1 Avenue Fresnel, 91767 Palaiseau, France.
authors.forename: A
authors.initials: A
authors.lastname: Dussaux
authors.affiliation: Unité Mixte de Physique CNRS/Thales and Université Paris Sud, 1 Avenue Fresnel, 91767 Palaiseau, France.
authors.forename: N
authors.initials: N
authors.lastname: Locatelli
authors.affiliation: Unité Mixte de Physique CNRS/Thales and Université Paris Sud, 1 Avenue Fresnel, 91767 Palaiseau, France.|National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Tsunegi
authors.affiliation: Unité Mixte de Physique CNRS/Thales and Université Paris Sud, 1 Avenue Fresnel, 91767 Palaiseau, France.
authors.forename: E
authors.initials: E
authors.lastname: Grimaldi
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kubota
authors.affiliation: Unité Mixte de Physique CNRS/Thales and Université Paris Sud, 1 Avenue Fresnel, 91767 Palaiseau, France.
authors.forename: P
authors.initials: P
authors.lastname: Bortolotti
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yakushiji
authors.affiliation: Unité Mixte de Physique CNRS/Thales and Université Paris Sud, 1 Avenue Fresnel, 91767 Palaiseau, France.
authors.forename: J
authors.initials: J
authors.lastname: Grollier
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Fukushima
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Yuasa
authors.affiliation: Unité Mixte de Physique CNRS/Thales and Université Paris Sud, 1 Avenue Fresnel, 91767 Palaiseau, France.
authors.forename: V
authors.initials: V
authors.lastname: Cros