Tunable Intrinsic Phase Shift Between a Spin Torque Nano-Oscillator and an AC Current
2007 (English)In: 2007 7th IEEE Conference On Nanotechnology, Vol 1-3, 2007, 229-232 p.Conference paper (Refereed)
We present magnetodynamic simulations, based on the Landau-Lifshitz-Gilbert-Slonczewski equations, of the interaction between a spin torque oscillator (STO) and an ac current (I(ac)). To avoide any extrinsic phase shift we inject the ac current at the intrinsic frequency (f(STO)) of the STO. We nevertheless find an unexpected intrinsic preferred phase shift Delta(phi 0) between the STO and I. In the in-plane precession mode (IP) the STO adjusts to a state where its resistance (or voltage) lags lac about a quarter of a wave length (Delta(phi 0)=87-94 degrees). In this regime Delta(phi 0) increases somewhat with the dc current. However, as the precession changes into the Out-Of-Plane (OOP) mode, Delta(phi 0) exhibits a dramatic jump by about 180 degrees, i.e. the STO resistance now precedes I(ac) about a quarter of a wave length (vertical bar Delta(phi 0)vertical bar=86 degrees). Delta(phi 0) can furthermore be tuned by changing one or more of the anisotropy field, the demagnetizing field or the applied field. At the IP/OOP boundary, the ac current mixes the two oscillation modes and both chaotic and periodic mixing is observed. We argue that 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. 229-232 p.
phase shift, spin torque oscillator, in-plane oscillation, out-of-plane oscillation
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-41105DOI: 10.1109/NANO.2007.4601177ISI: 000261434900050ScopusID: 2-s2.0-52949143153ISBN: 978-1-4244-0607-4OAI: oai:DiVA.org:kth-41105DiVA: diva2:443795
7th IEEE Conference on Nanotechnology Location: Hong Kong,China, Date: AUG 02-05, 2007