Perturbation of magnetostatic modes observed by ferromagnetic resonance force microscopy (original) (raw)
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Ferromagnetic resonance of a YIG film in the low frequency regime
Journal of Applied Physics, 2016
An improved method for characterizing the magnetic anisotropy of films with cubic symmetry is described and is applied to an yttrium iron garnet (111) film. Analysis of the FMR spectra performed both in-plane and out-of-plane from 0.7 to 8 GHz yielded the magnetic anisotropy constants as well as the saturation magnetization. The field at which FMR is observed turns out to be quite sensitive to anisotropy constants (by more than a factor ten) in the low frequency (< 2 GHz) regime and when the orientation of the magnetic field is nearly normal to the sample plane; the restoring force on the magnetization arising from the magnetocrystalline anisotropy fields is then comparable to that from the external field, thereby allowing the anisotropy constants to be determined with greater accuracy. In this region, unusual dynamical behaviors are observed such as multiple resonances and a switching of FMR resonance with only a 1 degree change in field orientation at 0.7 GHz.
Physical Review B, 2009
We present Magnetic Resonance Force Microscopy (MRFM) measurements of Ferromagnetic Resonance (FMR) in a 50 nm thick permalloy film, tilted with respect to the direction of the external magnetic field. At small probe-sample distances the MRFM spectrum breaks up into multiple modes, which we identify as local ferromagnetic resonances confined by the magnetic field of the MRFM tip. Micromagnetic simulations support this identification of the modes and show they are stabilized in the region where the dipolar tip field has a component anti-parallel to the applied field.
Local Excitation of Magnetostatic Modes in YIG
IEEE Transactions on Magnetics, 2013
Described are ferromagnetic resonance (FMR) studies of the long wavelength magnetostatic wave modes of a single crystal yttrium iron garnet (YIG) slab magnetized by an in-plane field. A resonant circuit comprising a coil, 50 m in diameter, is used to excite and detect the YIG microwave absorption spectrum. By changing its orientation and position over the sample surface it is possible to excite selectively different series of magnetostatic modes. The observed resonance fields are in good agreement with those calculated numerically from the Damon-Eshbach dispersion relation. The effect of heat currents on the magnetization dynamics in insulating magnets is explored. For a YIG crystal 10 mm in length, 2 mm in width and 25 micrometers in thickness, a temperature gradient of about 20 K/cm is sufficient to suppress the high-order longitudinal magnetostatic modes.
We present Magnetic Resonance Force Microscopy (MRFM) measurements of Ferromagnetic Resonance (FMR) in a 50 nm thick permalloy film, tilted with respect to the direction of the external magnetic field. At small probe-sample distances the MRFM spectrum breaks up into multiple modes, which we identify as local ferromagnetic resonances confined by the magnetic field of the MRFM tip. Micromagnetic simulations support this identification of the modes and show they are stabilized in the region where the dipolar tip field has a component anti-parallel to the applied field.
Applied Physics A Solids and Surfaces, 1993
The conventional and photothermally modulated (PM) ferromagnetic resonance (FMR) of magnetostatic modes (MSM) in yttrium iron garnet (YIG) films have been investigated as a function of temperature. Approaching the ferrimagnetic transition at Tc = 560 K a strong enhancement of the PM-FMR signal amplitude is observed which is accompanied by a change of the signal shape. The observations are discussed in the framework of a model that takes into account the temperature derivatives of those quantifies that contribute to the high-frequency susceptibility. At temperatures still below Tc a paramagnetic line emerges. The MSM disappear in a state of finite magnetization which is explained on the basis of damping of the MSM being important in the vicinity of the magnetic phase transition. Additionally, frequency and power dependent measurements are presented and the imaging ability of PM-FMR is demonstrated.
Ferromagnetic resonance of single-crystal YIG/gadolinium gallium garnet/YIG layers
Journal of Applied Physics, 1990
Evolution of ferromagnetic and spin-wave resonances with crystalline order in thin films of full-Heusler alloy Co2MnSi J. Appl. Phys. 111, 023912 Frequency-selective control of ferromagnetic resonance linewidth in magnetic multilayers Appl. Phys. Lett. 100, 032402 Spin wave modes in ferromagnetic tubes J. Appl. Phys. 111, 013905 Hysteretic spin-wave excitation in spin-torque oscillators as a function of the in-plane field angle: A micromagnetic description J. Appl. Phys. 110, 123913 Multi-domain resonance in textured Z-type hexagonal ferrite
Imaging mechanisms of force detected FMR microscopy
Journal of Applied Physics, 2000
We demonstrate spatial resolution of ferromagnetic resonance in a microscopic sample of YIG using ferromagnetic resonance force microscopy ͑FMRFM͒. Measurements were performed on a small single crystal YIG film grown on a GGG substrate, roughly rectangular in shape 20 mϫϳ150 m and 3 m thick. The perpendicular and parallel force geometries of FMRFM, in conjunction with an external bias field both parallel and perpendicular to the film, were used to scan the sample. This enabled the detection of strong signals, even at atmospheric pressure and room temperature. The fundamental and higher-order magnetostatic modes were observed to have 26-29 Gauss separation. The intensity of these modes exhibited spatial variation as the magnetic tip was scanned over the sample, and this behavior is qualitatively explained by DE theory. An improved fabrication method for magnet on cantilever was employed, which yielded a spatial resolution of 15 m. These results demonstrate the potential of FMRFM for investigating the spatial dependence of ferromagnetic resonance, and for studying the anisotropy fields and exchange coupling effects within multilayer films and small magnetic systems.
Journal of Physics D: Applied Physics, 2014
Measurements of the exchange stiffness D and the exchange constant A of Yttrium Iron Garnet (YIG) films are presented. The YIG films with thicknesses from 0.9 µm to 2.6 µm were investigated with a microwave setup in a wide frequency range from 5 to 40 GHz. The measurements were performed when the external static magnetic field was applied in-plane and out-of-plane. The method of Schreiber and Frait [1], based on the analysis of the perpendicular standing spin wave (PSSW) mode frequency dependence on the applied out-of-plane magnetic field, was used to obtain the exchange stiffness D. This method was modified to avoid the influence of internal magnetic fields during the determination of the exchange stiffness. Furthermore, the method was adapted for in-plane measurements as well. The results obtained using all methods are compared and values of D between (5.18 ± 0.01) • 10 −17 T•m 2 and (5.34±0.02)•10 −17 T•m 2 were obtained for different thicknesses. From this the exchange constant was calculated to be A = (3.65 ± 0.38) pJ/m.
Controlling Gilbert damping in a YIG film using nonlocal spin currents
Physical Review B, 2016
We demonstrate the control of Gilbert damping in 65-nm-thick yttrium iron garnet (YIG) films using a spin-polarized current generated by a direct current through a nanocontact, spin filtered by a thin Co layer. The magnetodynamics of both the YIG and the Co layers can be excited by a pulse-modulated microwave current injected through the nanocontact and the response detected as a lock-in amplified voltage over the device. The spectra show three clear peaks, two associated with the ferromagnetic resonance (FMR) in each layer, and an additional Co mode with a higher wave vector proportional to the inverse of the nanocontact diameter. By varying the sign and magnitude of the direct nanocontact current, we can either increase or decrease the linewidth of the YIG FMR peak consistent with additional positive or negative damping being exerted by the nonlocal spin current injected into the YIG film. Our nanocontact approach thus offers an alternative route in the search for auto-oscillations in YIG films.