Resonances in Ferromagnetic Gratings Detected by Microwave Photoconductivity

Gui, Yang; Holland, Steffen; Mecking, N.; Hu, Chang‐Ming

doi:10.1103/physrevlett.95.056807

Cited by 29 publications

(32 citation statements)

References 21 publications

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“…1͑c͒ that the EDFMR signal intensity increases linearly with P MW over more than two decades, as also observed by others. 3,4 Simultaneously, the FMR signal intensity increases as ͱ P MW ͓Fig. 1͑c͔͒, as expected for conventional FMR below saturation.…”

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confidence: 60%

“…16,17 To allow for a direct comparison between the conventional FMR signal and the microwave-induced resistivity changes, we have plotted the resistivity data under microwave irradiation from sistance can be unambiguously identified as an EDFMR. [2][3][4] Note that all FMR modes in the conventional FMR signal are reproduced in the EDFMR trace with good fidelity. The slight discrepancies in signal shape and intensity between EDFMR and FMR are due to the bolometric nature of the EDFMR signal, as discussed below.…”

mentioning

confidence: 99%

“…6 These effects can be used to detect FMR in magnetic micro-and nanostructures. 4,6 This is attractive, as FMR is one of the most sensitive methods for the investigation of magnetic anisotropy. However, to exploit the potential of such novel FMR detection methods, their full equivalence with the well established conventional cavity-based FMR must first be demonstrated.…”

mentioning

confidence: 99%

“…However, Gui et al invoke eddy currents as the origin. 4 The time constant in Eq. ͑1͒ is of the order of several seconds.…”

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confidence: 99%

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Electrically detected ferromagnetic resonance

Goennenwein

Schink

Brandlmaier

et al. 2007

Applied Physics Letters

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We study the magnetoresistance properties of thin ferromagnetic CrO 2 and Fe 3 O 4 films under microwave irradiation. Both the sheet resistance and the Hall voltage V Hall characteristically change when a ferromagnetic resonance ͑FMR͒ occurs in the film. The electrically detected ferromagnetic resonance ͑EDFMR͒ signals closely match the conventional FMR, measured simultaneously, in both resonance fields and line shapes. The sign and the magnitude of the resonant changes ⌬ / and ⌬V Hall / V Hall can be consistently described in terms of a Joule heating effect. Bolometric EDFMR thus is a powerful tool for the investigation of magnetic anisotropy and magnetoresistive phenomena in ferromagnetic micro-or nanostructures. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2722027͔The occurrence of ferromagnetic resonance ͑FMR͒ affects the quasistatic properties of a magnetic material, such as its magnetoresistance, 1-4 magnetoimpedance, 5 or caloric properties. 6 These effects can be used to detect FMR in magnetic micro-and nanostructures. 4,6 This is attractive, as FMR is one of the most sensitive methods for the investigation of magnetic anisotropy. However, to exploit the potential of such novel FMR detection methods, their full equivalence with the well established conventional cavity-based FMR must first be demonstrated. In semiconductors, the effect of paramagnetic resonance on transport processes is well known. 7-9 Here, we report on nonresonant and resonant changes of the magnetoresistance of thin ferromagnetic CrO 2 and Fe 3 O 4 films upon microwave irradiation. We show that these electrically detected ferromagnetic resonance ͑ED-FMR͒ signals are spectroscopically equivalent to conventional FMR measured simultaneously, and that the sign and the magnitude of the EDFMR signals can be quantitatively understood in terms of a Joule heating effect. This opens the way to selectively investigate particular transport processes in ferromagnets via magnetic resonance techniques.The single-crystalline, 100 nm thick CrO 2 films studied were deposited on ͑100͒-oriented TiO 2 substrates by chemical vapor deposition. 10 After patterning them into 80 m wide and 600 m long Hall bar structures using optical lithography and wet chemical etching, we fabricated Ohmic contacts by depositing Au in situ immediately after sputter cleaning the film surface in an Ar plasma. 11 The magnetite ͑Fe 3 O 4 ͒ samples were grown on ͑100͒-oriented MgO substrates by pulsed laser deposition. 12 Here, we study a 32 nm thick, coherently strained Fe 3 O 4 film with Ohmic contacts in van der Pauw geometry, realized by wedge bonding Al wires.The FMR spectra were measured in an X-band ͑9 GHz͒ electron spin resonance setup at room temperature as a function of a static magnetic field H, using magnetic field modulation at 100 kHz with an amplitude 0 ⌬H = 3.2 mT. Simultaneously to the FMR, we recorded the longitudinal magnetoresistance or the Hall effect in the samples in fourpoint geometry, with ac current bias I at a frequency I ഛ 1.1 kHz. The magnetiza...

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confidence: 60%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…However, Gui et al invoke eddy currents as the origin. 4 The time constant in Eq. ͑1͒ is of the order of several seconds.…”

mentioning

confidence: 99%

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Electrically detected ferromagnetic resonance

Goennenwein

Schink

Brandlmaier

et al. 2007

Applied Physics Letters

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“…19,20 The general problem of these methods is the rectification effects at the ferromagnet/normal-metal contact, which can suppress or mimic the spin pumping signal. [21][22][23] Thus, the identification of these spurious effects is crucial and represents one of the main themes of this paper.…”

Section: Introductionmentioning

confidence: 99%

Electrical detection of spin pumping: dc voltage generated by ferromagnetic resonance at ferromagnet/nonmagnet contact

et al. 2008

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We describe electrical detection of spin pumping in metallic nanostructures. In the spin pumping effect, a precessing ferromagnet attached to a normal metal acts as a pump of spin-polarized current, giving rise to a spin accumulation. The resulting spin accumulation induces a backflow of spin current into the ferromagnet and generates a dc voltage due to the spin dependent conductivities of the ferromagnet. The magnitude of such voltage is proportional to the spin-relaxation properties of the normal metal. By using platinum as a contact material we observe, in agreement with theory, that the voltage is significantly reduced as compared to the case when aluminum was used. Furthermore, the effects of rectification between the circulating rf currents and the magnetization precession of the ferromagnet are examined. Most significantly, we show that using an improved layout device geometry, these effects can be minimized.

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Ferromagnetic Resonance

Mewes

2021

Magnetic Measurement Techniques for Materials Characterization

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January 2010 he is an academic partner of the Niğde University. His current research interests include ferromagnetic resonance, microwave technology, magnetic nanostructures (nanowires, nanoparticles and magnetic nano O-ring), and spin-Peierls systems. Dr. Yalçın has published many papers in journals listed in the Science Citation Index, and several invited chapters in books released by international publishers.

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Resonances in Ferromagnetic Gratings Detected by Microwave Photoconductivity

Cited by 29 publications

References 21 publications

Electrically detected ferromagnetic resonance

Electrically detected ferromagnetic resonance

Electrical detection of spin pumping: dc voltage generated by ferromagnetic resonance at ferromagnet/nonmagnet contact

Ferromagnetic Resonance

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