			Home About us Contact

Ferromagnetic Resonance (ferromagnetic + resonance)

Distribution by Scientific Domains

Polymers and Materials Science	20%

Selected Abstracts

FMR study of strain-induced magnetic anisotropies in CrO2 thin films

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 15 2004
B. Z. Rameev
Abstract Epitaxial CrO2 thin films were grown on TiO2 (100) single-crystalline substrates by chemical vapour deposition (CVD) process with use of CrO3 solid precursor. The films with different thickness (27,530 nm) were studied by Ferromagnetic Resonance (FMR) technique. Strong dependence of FMR signal on the film thickness was observed in the series of CrO2 films deposited onto the pre-etched TiO2 substrates. It is shown that the magnetic behaviour of the CrO2 films arises from competition between magnetocrystalline and strain anisotropies that favour the [001] and [010] magnetization directions, respectively. For the thinnest film the strain anisotropy dominates, and the magnetic easy axis switches from [001] to the [010] direction. On the contrary, the CrO2 film grown on the unetched substrate demonstrates essentially strain-free magnetic anisotropy behaviour. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Giant Electric Field Tuning of Magnetic Properties in Multiferroic Ferrite/Ferroelectric Heterostructures

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2009
Ming Liu
Abstract Multiferroic heterostructures of Fe3O4/PZT (lead zirconium titanate), Fe3O4/PMN-PT (lead magnesium niobate-lead titanate) and Fe3O4/PZN-PT (lead zinc niobate-lead titanate) are prepared by spin-spray depositing Fe3O4 ferrite film on ferroelectric PZT, PMN-PT and PZN-PT substrates at a low temperature of 90,°C. Strong magnetoelectric coupling (ME) and giant microwave tunability are demonstrated by a electrostatic field induced magnetic anisotropic field change in these heterostructures. A high electrostatically tunable ferromagnetic resonance (FMR) field shift up to 600,Oe, corresponding to a large microwave ME coefficient of 67,Oe cm kV,1, is observed in Fe3O4/PMN-PT heterostructures. A record-high electrostatically tunable FMR field range of 860 Oe with a linewidth of 330,380,Oe is demonstrated in Fe3O4/PZN-PT heterostructure, corresponding to a ME coefficient of 108,Oe cm kV,1. Static ME interaction is also investigated and a maximum electric field induced squareness ratio change of 40% is observed in Fe3O4/PZN-PT. In addition, a new concept that the external magnetic orientation and the electric field cooperate to determine microwave magnetic tunability is brought forth to significantly enhance the microwave tunable range up to 1000,Oe. These low temperature synthesized multiferroic heterostructures exhibiting giant electrostatically induced tunable magnetic resonance field at microwave frequencies provide great opportunities for electrostatically tunable microwave multiferroic devices. [source]

Giant Electric Field Tuning of Magnetism in Novel Multiferroic FeGaB/Lead Zinc Niobate,Lead Titanate (PZN-PT) Heterostructures

ADVANCED MATERIALS, Issue 46 2009
Jing Lou
A novel multiferroic heterostructure consisting of a FeGaB thin film and a PZN-PT single crystal slab shows giant tunability of the ferromagnetic resonance (FMR) frequency of the heterostructure by electric field (see figure). The overall electric-field-induced FMR frequency change of 5.82 GHz is the largest reported so far. FeGaB/PZN-PT multiferroic heterostructures are promising candidates for wide-band electrostatically tunable microwave devices. [source]

Growth of magnetite epitaxial thin films by gas flow sputtering and characterization by FMR

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2007
Hiroshi Sakuma Member
Abstract The growth of magnetite (Fe3O4) epitaxial thin films on MgO substrates were studied by using gas flow sputtering (GFS). Reflection high-energy electron diffraction (RHEED) and atomic force microscopy showed that the surfaces of the films obtained at a substrate temperature Ts of 300 °C and oxygen flow rates FO2 of 0.12 , 0.18 sccm are fairly flat for the film thickness of about 200 nm. The saturation magnetization and resistivity were close to the reported values of Fe3O4 for Ts= 300°C and FO2 = 0.12,0.20sccm. The films obtained at Ts= 300°C and FO2=0.16 and 0.18 sccm showed Verwey transition, which is persuasive evidence of the formation of Fe3O4. The epitaxial relationship of Fe3O4(100)//MgO(100) and Fe3O4[100]//MgO[100] was confirmed by using ferromagnetic resonance (FMR), and the anisotropy constants and magnetization were obtained by the fitting of resonance-field versus applied-field angle curves. © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

Integrated Microwave and Optical Scanning Probe for Magnetic Resonance Imaging

ISRAEL JOURNAL OF CHEMISTRY, Issue 1 2008
Fadi Sakran
We demonstrate a scanning microwave near-field probe based on a slit aperture that is capable of performing spatially-resolved magnetic resonance measurements in the frequency range of 3,90 GHz. We demonstrate local electron spin resonance (ESR), ferromagnetic resonance (FMR), and spin-wave resonance (SWR) studies on model materials. The probe can serve as a local contactless heater as well. We demonstrate also a further application, a dual microwave/optical near-field probe that can be useful in contactless measurements of photoconductivity and fluorescence under microwave irradiation. [source]

Low-field non-resonant microwave absorption in glass-coated Co-rich microwires

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 4 2009
Raul Valenzuela
Abstract A study of low-field non-resonant microwave absorption (LFA) at 9.8 GHz, on as-cast amorphous Co-rich CoFeBSi microwires under different measuring geometries is presented. Results confirm that LFA is associated with the magnetization processes from the unmagnetized state (HDC = 0) to the saturated condition, in many aspects similar to Giant Magnetoimpedance (GMI), and clearly different from ferromagnetic resonance (FMR). LFA signal showed large variations in its maximum,minimum separation as a function of the measuring geometry, which is interpreted in terms of the total anisotropy in the process. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Longitudinal and transverse incremental permeability of Co19.35Fe53.28Hf7.92O19.35 films

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 12 2007
Anh-Tuan Le
Abstract We present here, the results of a thorough study of the longitudinal permeability ratio (LPR) and transverse permeability ratio (TPR) in sputtered Co19.35Fe53.28Hf7.92O19.35 films with varying thicknesses (t = 1, 1.5, 1.8 and 2.4 µm) in the frequency range of 100 - 1000 MHz. It is found that for all samples investigated, the LPR/TPR first increases with increasing frequency, reaches a maximum at 710 MHz, and then decreases at higher frequencies. This is related to the ferromagnetic resonance. The LPR and TPR profiles measured along the easy axis of the film show a single-peak feature, whereas those measured along the hard axis of the film show a double-peak one. This indicates an existence of magnetic anisotropy and its dispersion in the films. It reveals that the study of LPR and TPR spectra provides an alternative way for the evaluation of the high-frequency magnetic softness of film-type materials. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Anisotropic FMR-linewidth of triple-domain Fe layers on hexagonal GaN(0001)

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2006
M. Buchmeier
Abstract We present a ferromagnetic resonance (FMR) study of Fe films with thicknesses between 5 and 70 nm prepared by electron-beam evaporation on top of hexagonal GaN(0001). X-ray diffraction (XRD) and low-energy electron diffraction (LEED) suggest the growth in crystallographic Fe(110) domains with three different orientations. The magnetic properties have been investigated by in-plane angle-dependent FMR at frequencies between 4.5 to 24 GHz. All samples show a hexagonal in-plane anisotropy with the easy axes oriented parallel to the Fe [001] directions. The anisotropy field strength of about 8 mT reveals a bulk-like thickness dependence. Therefore, we can exclude the following origins of anisotropy: (i) interface effects because of the bulk-like thickness dependence and (ii) averaged first order cubic or uniaxial anisotropies arising from the three grain orientations because of the relative strengths. We qualitatively explain the sixfold anisotropy by spin relaxation inside the grains. The FMR linewidth versus frequency curves are linear with almost no zero-frequency offset indicating a good homogeneity of the magnetic properties over the sample area. However, the effective damping parameter , shows pronounced anisotropy and thickness dependence, with enhanced damping along the hard axes and for thicker layers. We suggest that the additional damping can be explained by two-magnon scattering at defects which are due to the triple domain structure. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

FMR study of ultrahigh vacuum e-beam evaporated Co23Cu77 nanogranular films: Magnetotransport properties

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2006
R. Mustafa Öksüzoglu
Abstract The magnetic, magnetotransport and structural properties of Co23Cu77 granular thin films (7,43 nm) have been investigated using ferromagnetic resonance (FMR) and high-resolution XRD techniques. Co particles possess a crystalline fcc structure in the investigated films. A correlation between the GMR effect and the anisotropy field has been found, which increases with increasing film thickness. Temperature-dependent FMR measurements revealed a blocking effect, which results from the competition of long range dipole,dipole interaction and anisotropy fields of Co particles. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

FMR study of amorphous Co68Mn7Si10B15 glass-coated microwires

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003
R. Zuberek
Abstract The magnetic properties of Co68Mn7Si10B15 glass coated amorphous microwires of about 16.5 ,m in diameter have been investigated from liquid helium up to room temperature by ferromagnetic resonance at 9.243 GHz. Based on the results of measurements both the magnetic anisotropy constants, the first arising from the stress at the interface between the metallic surface and the coating and the second one of the inner core have been obtained for the room temperature. The effective anisotropy field was determined in the range from the liquid helium to the room temperature. [source]