Berlin 2008 – scientific programme
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MA: Fachverband Magnetismus
MA 28: Magnetic Thin Films III
MA 28.8: Talk
Thursday, February 28, 2008, 16:15–16:30, H 1012
AMR-induced microwave photoresistance and photovoltage in ferromagnetic films — •Nikolai Mecking1,2, Yongsheng Gui1, and Can-Ming Hu1 — 1Dep. of Physics, University of Manitoba, Winnipeg, Canada — 2IAP, Uni Hamburg, Jungiusstr. 11, 20355 Hamburg
We have investigated the microwave photoresistance (PR) and photovoltage (PV) of photolithographically stripe shaped ferromagnetic Ni80Fe20-films [1-3]. Along these we find maximal AMR with parallel magnetization M and minimal AMR with perpendicular M. However, excited to precess M shifts and the AMR decreases in the parallel case (negative PR) and increases in the perpendicular case (positive PR) [1]. Additionally M precession causes an AMR oscillation that partially rectifies the microwave current I (PV). M can be excited through FMR [1], standing exchange spin waves [2] or magnetostatic modes [3]. These are very sensitively detected during magnetic field sweeps and show a linear combination of dispersive and Lorentz line shape whose ratio is determined by the phase difference between M and I [1]. So, while the PR shows only Lorentz line shape, the PV gives us an insight into the phase of M. Moreover, due to the ferromagnetic susceptibility anisotropy we can distinguish the PV portions arising from the different spatial components of the exciting microwave magnetic field and resolve their phase [1] what is interesting for magnetic field sensing. We acknowledge support from BMBF 01BM461, SFB 508 and the DAAD.
[1] N. Mecking, Y.S. Gui, and C.-M. Hu, ArXiv/cond-mat 0710.1974.
[2] Y.S. Gui, N. Mecking et al., PRL 98, 107602 (2007).
[3] Y.S. Gui, N. Mecking, and C.-M. Hu, PRL 98, 217603 (2007).