Microwave photovoltage and photoresistance effects in ferromagnetic microstrips

Mecking, N.; Gui, Y. S.; Hu, C.‐M.

doi:10.1103/physrevb.76.224430

Cited by 182 publications

(138 citation statements)

References 36 publications

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“…In this technique, a microwave current I ac in the CPS generates a microwave magnetic field nearly perpendicular to the sample plane at the nanowire location and excites spin wave eigenmodes in the Py wire when the frequency of I ac coincides with its spin wave eigenmode frequencies. Excitation of the spin wave eigenmodes results in a small change δR in the time-average wire resistance that arises from anisotropic magnetoresistance (AMR) of Py 23,47,48 . This resistance variation is then measured as a function of H. Peaks in δR(H) such as those shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

Spin wave eigenmodes in transversely magnetized thin film ferromagnetic wires

et al. 2015

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We report experimental and theoretical studies of spin wave eigenmodes in transversely magnetized thin film Permalloy wires. Using broadband ferromagnetic resonance technique, we measure the spectrum of spin wave eigenmodes in individual wires as a function of magnetic field and wire width. Comparison of the experimental data to our analytical model and micromagnetic simulations shows that the intrinsic dipolar edge pinning of spin waves is negligible in transversely magnetized wires. Our data also quantify the degree of extrinsic edge pinning in Permalloy wires. This work establishes the boundary conditions for dynamic magnetization in transversely magnetized thin film wires for the range of wire widths and thicknesses studied, and provides a quantitative description of the spin wave eigenmode frequencies and spatial profiles in this system as a function of the wire width.

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Section: Methodsmentioning

confidence: 99%

Spin wave eigenmodes in transversely magnetized thin film ferromagnetic wires

et al. 2015

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“…effect) [1,2,[7][8][9][10], and flowing of pure spin current across the interface of FM with adjacent non-magnetic ("normal") metal (NM) [9,[11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Resonance spin–charge phenomena and mechanism of magnetoresistance anisotropy in manganite/metal bilayer structures

Ацаркин¹,

Sorokin²,

Borisenko³

et al. 2016

J. Phys. D: Appl. Phys.

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The dc voltage generated under ferromagnetic resonance has been studied in bilayer structures based on manganite thin epitaxial films La 0.67 Sr 0.33 MnO 3 (LSMO) and non-magnetic metals (Au, Pt, and SrRuO 3 ) in the temperature range up to the Curie point. The effect is shown to be caused by two different phenomena: (1) the resonance dc electromotive force related to anisotropic magnetoresistance (AMR) in the manganite film and (2) pure spin current (spin pumping) registered by means of the inverse spin Hall effect in normal metal. The two phenomena were separated using the angular dependence of the effect, the external magnetic field H 0 being rotated in the film plane. It was found that the AMR mechanism in the manganite films differs substantially from that in traditional ferromagnetic metals being governed by the colossal magnetoresistance together with the in-plane magnetic anisotropy. The spin pumping effect registered in the bilayers was found to be much lower than that reported for common ferromagnets; possible reasons are discussed.

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“…These oscillations have spatially varying a.c. phases. Due to photoresistance 16 , the auto-oscillation leads to a change in d.c. resistance of each region. Summed over the whole sample, this change is given by…”

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confidence: 99%

Exchange magnon induced resistance asymmetry in permalloy spin-Hall oscillators

Langenfeld

Tshitoyan

Fang

et al. 2016

Applied Physics Letters

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We investigate magnetization dynamics in a spin-Hall oscillator using a direct current measurement as well as conventional microwave spectrum analysis. When the current applies an anti-damping spin-transfer torque, we observe a change in resistance which we ascribe to the excitation of incoherent exchange magnons. A simple model is developed based on the reduction of the effective saturation magnetization, quantitatively explaining the data. The observed phenomena highlight the importance of exchange magnons on the operation of spin-Hall oscillators.The combination of the spin-Hall effect and the spintransfer torque may be used to compensate the magnetic damping of a ferromagnet, facilitating precession of the macroscopic magnetization by the application of a direct current 1-5 . Such a device, a spin-Hall oscillator, is patterned in a simple current in-plane geometry and contains no tunnel barriers. The ability of the spin-Hall effect to apply a spin-current transverse to the chargecurrent enables the use of conducting magnetic materials as well as low-damping, insulating materials like yttriumiron-garnet (YIG) 5 . This is in contrast to conventional spin-torque nano-oscillators where a spin-polarized current is passed into a conducting ferromagnetic layer 6 . Despite being attractive due to their geometric simplicity and flexibility in choice of magnetic materials, for spin-Hall oscillators to become competitive with conventional spin-torque nano-oscillators, sources of damping such as spin-pumping 7 and multi-magnon scattering via exchange magnons 8,9 should be addressed in order to reduce the linewidth and increase the power generation efficiency. In this Letter we show that the current induced excitation of incoherent exchange magnons can be observed using a direct current measurement. We find a change in the sample resistance which correlates with the reduction of saturation magnetization taken from our spectroscopy measurements, similar to previously reported results 9 . Both phenomena are consistent within a simple model only utilizing the precession cone-angle of the auto-oscillatory exchange magnons.The sample is a Pt(3)/Py(4)/AlO x (1.6) trilayer deposited by d.c. magnetron sputtering onto a MgO substrate. Numbers in parentheses give thicknesses in nanometers. The multilayer is patterned into a 500 nm × 6 µm bar via electron-beam lithography and subsequent Ar ion milling. Adjacent evaporated Cr(5)/Au(50) pads a) current address: Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany b) ajf1006@cam.ac.uk serve as contact pads. When current is applied to this structure, the portion of the current flowing inside the heavy metal (platinum) generates an out-of-plane spincurrent via the spin-Hall effect (SHE). This spin-current exerts a spin-transfer torque (STT) on the magnetization of the ferromagnetic layer (permalloy) 10,11 , which can oppose the magnetic damping, leading to a change in the Gilbert damping parameter α 12,13 :Here, α 0 is the pristine damping parameter, j c,hm is the charge-curren...

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Microwave photovoltage and photoresistance effects in ferromagnetic microstrips

Cited by 182 publications

References 36 publications

Spin wave eigenmodes in transversely magnetized thin film ferromagnetic wires

Spin wave eigenmodes in transversely magnetized thin film ferromagnetic wires

Resonance spin–charge phenomena and mechanism of magnetoresistance anisotropy in manganite/metal bilayer structures

Exchange magnon induced resistance asymmetry in permalloy spin-Hall oscillators

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