Variation of magnetization and the Landé g factor with thickness in Ni–Fe films (original) (raw)

Effect of Ta-Underlayer on Thickness Dependent Magnetic Properties of Ni-Fe Films

IEEE Transactions on Magnetics, 2015

We report the effect of Ta underlayer on the structural and magnetic properties of Permalloy (Ni81Fe19) thin films over a wide range of film thicknesses (tNi-Fe = 10-200 nm). For this purpose, Ta (5 nm)/Ni-Fe (tNi-Fe nm)/Ta (2 nm) films were grown on thermally oxidized Si substrates under the presence and absence of biasing magnetic field (1000 Oe). The Ni-Fe films grown under the presence and absence of biasing magnetic fields are referred as Ta/Ni-Fe(M) and Ta/Ni-Fe(NM), respectively. X-ray diffraction studies revealed that the Taunderlayer plays an important role in the formation of fcc-(111) Ni-Fe texture in both Ta/Ni-Fe(M) and Ta/Ni-Fe(NM) films. In addition, the values of average crystallite size depend on the film thickness, biasing field and Ta underlayer. Thickness dependent magnetic hysteresis (M-H) loops demonstrate a strong in-plane uniaxial anisotropy in both Ta/Ni-Fe(NM) and Ta/Ni-Fe(M) films. The uniaxial anisotropy constant (Ku) depends not only on the film thickness, but also strongly on the biasing magnetic field. Coercivity decreases with increasing film thickness for both Ta/Ni-Fe(NM) and Ta/Ni-Fe(M) films and approaches to a minimum of about 0.4 Oe even at tNi-Fe = 200 nm. Furthermore, the observed magnetic domain patterns of Ni-Fe films show their dependency on the Ta underlayer, biasing field and Ni-Fe thickness. The effects of Ta underlayer, Ni-Fe film thickness and the biasing-field driven uniaxial anisotropy on the structural and magnetic properties are discussed on the basis of reduction in strain at the Ta/Ni-Fe interface.

A study on the thickness dependence of static and dynamic magnetic properties of Ni81Fe19 thin films

Journal of Magnetism and Magnetic Materials, 2016

A set of Permalloy thin films with thicknesses ranging from 100 nm to 1000 nm have been investigated by in-plane hysteresis loops, magnetic torque, microwave permeability and X-ray diffraction measurements. The frequency evolution of the complex permeability was treated within the Debye relaxation model allowing the obtainment of the resonance frequency, resonance linewidth and the rotational component of the permeability at each applied field. The samples can be separated in three groups according their magnetic properties. Samples with thickness until 150 nm present magnetic properties typical of a system with a well defined in-plane uniaxial anisotropy and just one resonance frequency in the high frequency permeability spectra. Samples with thicknesses above 300 nm present magnetization loops almost isotropic in-plane and two resonance frequencies in the permeability spectra. The samples at the intermediate thickness range present some characteristic from thinner and other of the thicker group. Ferromagnetic resonance and torque measurements have detected the presence of a small uniaxial anisotropy even in the thicker group of samples. The multiple ferromagnetic resonances in the permeability spectra present in the thicker group of samples were treated as non-interacting magnetic systems. These characteristics were attributed to the appearance of stripe domains together with a rotatable anisotropy, due to an out-of-plane magnetization component. The relaxation mechanisms which give rise to the resonance linewidth were discussed considering two possible sources, Gilbert damping and anisotropy dispersion. While the Gilbert damping was almost the same for all samples it was verified the anisotropy dispersion increase with the thickness.

Inhomogeneous magnetic field influence on magnetic properties of NiFe/IrMn thin film structures

Journal of Magnetism and Magnetic Materials, 2019

We demonstrate how the configuration and magnitude of a magnetic field, applied during magnetron sputtering of a NiFe/IrMn bilayer, influence the magnetic properties of the structure, such as hysteresis loop shape, coercivity, and exchange bias. Furthermore, we illustrate that it is possible to create a stepwise hysteresis loop in the sample's region with the highest field gradient. The found features can be used for future sensor applications.

Development of interface-induced out-of-plane magnetic anisotropy in Ni/Fe/Ni trilayers

Surface Science, 2001

The magnetic properties of trilayers Ni(1000 A)/ 57 Fe(x A)/Ni(200 A) grown by evaporation in ultra-high vacuum, have been investigated using M ossbauer spectroscopy, magneto-optic Kerr vector-magnetometry, and magnetic force microscopy (MFM). The data measured from a sample with Fe thickness x 6 A show the development of an out-ofplane anisotropy that tends to align the magnetization of the 57 Fe at about 40°respect to the normal to the layer plane. For higher 57 Fe layer thickness the data indicate that the magnetization lies in the ®lm plane. The magneto-optic measurements and the MFM images demonstrate also that when x 6 A the 57 Fe layer induces a reorientation of the magnetization of the Ni outermost layer from in-plane to out-of-plane. The results are interpreted as due to anisotropy eects induced at the interface Fe/Ni and to the c 3 a transition that takes place between 6 and 16 A.

A ferromagnetic resonance study of NiFe alloy thin films

NiFe alloy films with thicknesses in the range from 60 to 150 Å were sputtered onto Si (0 0 1) wafers by DC magnetron sputtering, and then characterized by in-plane ferromagnetic resonance technique (FMR) at x-band. The FMR field (H R ) and linewidth (DH) were studied as a function of the in-plane angle, j H , film thickness, t, and temperature, T. The main effects of temperature on the magnetic properties of these films is to increase the in-plane uniaxial anisotropy and to induce a surface anisotropy that pushes the magnetization out-of-plane. These anisotropies were found to vary with thickness and temperature. The main processes that determine the line broadening are the intrinsic conduction mechanism and the in-plane uniaxial dispersions. r

Magnetic profile of Ni/Fe/Ni trilayers

Journal of Magnetism and Magnetic Materials, 2000

The magnetic structure of Ni(1 1 1)/Fe/Ni trilayer was studied by MoK ssbauer spectroscopy. Two kinds of samples were studied di!ering each other in the substrate preparation, in the evaporation method of Fe and in vacuum condition. Fabrication by thermal evaporation in HV on a Ni bu!er layer grown on mica and by electron beam bombardment in UHV on cleaned Ni(1 1 1) single crystal was used. The Ni substrate morphology was characterised by STM. Similar magnetic structure was found for the two systems, consisting of two well-de"ned features of the hyper"ne "eld occurring at high value (&28 T) and low one ((8 T). The high-"eld component was assigned to Fe atoms close to Fe}Ni interface with high-spin ferromagnetic state, and the low-"eld component to Fe atoms inside the Fe layer with low-spin antiferromagnetic state.

Thickness-dependent magnetic properties of Ni81Fe19, Co90Fe10 and Ni65Fe15Co20 thin films

Journal of Magnetism and Magnetic Materials, 2002

We present results of magnetization and magnetic anisotropy measurements in thin magnetic films of the alloys Ni 81 Fe 19 ; Co 90 Fe 10 and Ni 65 Fe 15 Co 20 that are commonly used in magnetoelectronic devices. The films were sandwiched between layers of Ta. At room temperature the critical thickness for all the films to become ferromagnetic is in the range 11-13 ( A. In Co 90 Fe 10 the coercivity and the anisotropy field both depend strongly on layer thickness. r 0304-8853/02/$ -see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 -8 8 5 3 ( 0 2 ) 0 0 5 7 7 -2

The role of electron scattering in magnetization relaxation in thin Ni$_{81}$Fe$_{19}$ films

arXiv (Cornell University), 2002

We observe a strong correlation between magnetization relaxation and electrical resistivity in thin Permalloy (Ni81Fe19, "Py") films. Electron scattering rates in the films were affected by varying film thickness and deposition conditions. This shows that the magnetization relaxation mechanism is analogous to "bulk" relaxation, where phonon scattering in bulk is replaced by surface and defect scattering in thin films. Another interesting finding is the increased magnetization damping with Pt layers adjacent to the Py films. This is attributed to the strong spin-orbit coupling in Pt, resulting in spin-flip scattering of electrons that enter from the Py.

Surface morphology, structure and magnetic anisotropy in epitaxial Ni films

Journal of Alloys and Compounds, 2004

Understanding the correlation between film structure and its ferromagnetic properties is very important for applications. To this end, we have investigated epitaxial and smooth Ni films grown on MgO substrates using molecular beam epitaxy (MBE) and dc sputtering. To establish correlation between film morphology and structure with magnetic properties, we have used in situ and ex situ scanning tunneling microscopy (STM) images along with studies on the azimuthal dependence of the magnetization reversal utilizing longitudinal Kerr effect (MOKE). Our MOKE azimuthal studies on annealed MBE-grown (0 0 1) Ni films indicate additional uniaxial anisotropy possibly related to surface nano-patterning, superimposed to the expected four-fold symmetry due to magneto-crystalline anisotropy. This uniaxial anisotropy is absent in non-annealed MBE-grown (0 0 1) Ni films as well as sputtered annealed and non-annealed (0 0 1) Ni films. Conversely, neither annealed MBE-grown nor sputtered (1 1 1) oriented Ni films exhibit surface nano-patterning and their structural and magnetic properties exhibit identical azimuthal dependence.