Ferromagnetic resonance driven by spin transfer torque

Staudacher, T.; Tsoi, Maxim

doi:10.1016/j.tsf.2011.03.070

Cited by 3 publications

(3 citation statements)

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“…In conclusion, using homodyne based measurement techniques we provide an in-depth study of the magnetodynamics in a quasi-confined system, namely a NC patterned on an extended pseudo spin valve film stack. The observed spectra are highly asymmetric and cannot be explained by a single resonance mode, as has been done in the past 7,12 . Instead, each spectra is fit by a combination of two Lorentzians from which we can extract the FMR mode resonance field and linewidth.…”

Section: Discussionmentioning

confidence: 75%

“…In the NC geometry literature 7,[12][13][14][15]28 , the observed ST-FMR spectra of the NiFe-based free layers have been analyzed as a single resonance, despite a significant peak asymmetry hinting at additional contributions. The linewidth of this asymmetric peak has not been understood so far 7 .…”

Section: Introductionmentioning

confidence: 99%

“…While homodyne-detected FMR studies on magnetic tunnel junction (MTJ) and all-metallic spin valve nanopillar devices have dominated the literature [2][3][4][5][6] , there have been an increasing number of studies utilizing point-and nanocontacts (NCs) on extended multilayer film stacks 7,[12][13][14][15] . The NC geometry is particularly promising for high-frequency spin torque oscillators (NC-STOs) [16][17][18][19][20][21][22] and for the emerging field of ST-based magnonics, [23][24][25][26][27] where highly non-linear auto-oscillatory modes are utilized for operation.…”

Section: Introductionmentioning

confidence: 99%

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Homodyne-detected ferromagnetic resonance of in-plane magnetized nanocontacts: Composite spin-wave resonances and their excitation mechanism

et al. 2016

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This work provides a detailed investigation of the measured in-plane field-swept homodynedetected ferromagnetic resonance (FMR) spectra of an extended Co/Cu/NiFe pseudo spin valve stack using a nanocontact (NC) geometry. The magnetodynamics are generated by a pulsemodulated microwave current and the resulting rectified dc mixing voltage, which appears across the NC at resonance, is detected using a lock-in amplifier. Most notably, we find that the measured spectra of the NiFe layer are composite in nature and highly asymmetric, consistent with the broadband excitation of multiple modes. Additionally, the data must be fit with two Lorentzian functions in order to extract a reasonable value for the Gilbert damping of the NiFe. Aided by micromagnetic simulations, we conclude that (i) for in-plane fields the rf Oersted field in the vicinity of the NC plays the dominant role in generating the observed spectra, (ii) in addition to the FMR mode, exchange dominated spin waves are also generated, and (iii) the NC diameter sets the mean wavevector of the exchange dominated spin wave, in good agreement with the dispersion relation.

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Section: Discussionmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Homodyne-detected ferromagnetic resonance of in-plane magnetized nanocontacts: Composite spin-wave resonances and their excitation mechanism

et al. 2016

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Using giant magneto resistance stripes to efficiently generate direct voltage signals from alternating current excitations

Kleinlein

Ocker

Schmidt

2014

Applied Physics Letters

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We have developed all metal spintronic devices which convert an alternating current (AC) in-plane current into a direct current (DC) voltage without using external magnetic fields. The devices are based on the modulation of the magnetization of the free magnetic layer in an exchange biased giant magneto resistance nanowire by the current-induced Oersted field. They can be operated at frequencies extending into the GHz range, and the resistance is easily tunable by changing the wire length. The devices can be operated on- or off-resonance. Even off-resonance we demonstrate an efficiency of 0.7 mV DC-output voltage per 1 mW input power. At ferromagnetic resonance, the efficiency is increased and can be as high as 1.8 VW in zero magnetic field. The efficiency of the devices can also be tuned by applying external magnetic fields. The device performance is dominated by the interplay of the Oersted field and the shape anisotropy of the free layer, and for narrow wires the output signal becomes smaller while the possible range of external magnetic fields is extended. The nanowires are easily scalable allowing for higher output voltages or fine tuning of the resistance to match the impedance for RF applications.

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