Intrinsic phase shift between a spin torque oscillator and an alternating current
2007 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 9, 09A510- p.Article in journal (Refereed) Published
We report on a preferred phase shift Delta phi(0) between a spin torque oscillator (STO) and an alternating current (I-ac) injected at the intrinsic frequency (f(STO)) of the STO. In the in-plane (IP) precession mode the STO adjusts to a state where its resistance (or voltage) lags I-ac about a quarter of a wavelength [Delta phi(0)=(87-94)degrees]. In the IP mode Delta phi(0) increases somewhat with the direct current. As the precession changes into the out-of-plane (OOP) mode, Delta phi(0) jumps by about 180 degrees, i.e., the STO resistance now precedes I-ac about a quarter of a wavelength (Delta phi(0)=-86 degrees). At the IP/OOP boundary, the alternating current mixes the two oscillation modes and both periodic and chaotic oscillations are observed. As a consequence of mixing, subharmonic terms appear in the STO signal. The intrinsic Delta phi(0) will impact any circuit design based on STO technology and will, e.g., have direct consequences for phase locking in networks of serially connected STOs.
Place, publisher, year, edition, pages
2007. Vol. 101, no 9, 09A510- p.
IdentifiersURN: urn:nbn:se:kth:diva-16641DOI: 10.1063/1.2710740ISI: 000246567900121ScopusID: 2-s2.0-34248588611OAI: oai:DiVA.org:kth-16641DiVA: diva2:334683
Conference: 10th Joint Magnetism and Magnetic Materials Conference/International Magnetics Conference. Baltimore, MD. JAN 07-11, 2007 2010-08-052010-08-052011-09-12Bibliographically approved