Investigation of the Structural and Magnetic Properties of Thin Ferromagnetic Films PDF Download

Author: W. D. Doyle
Publisher:
ISBN:
Category : Ferromagnetic materials
Languages : en
Pages : 50

View

Book Description
The principle object of the research is the correlation of the magnetic and structural properties of thin ferromagnetic films. Described in detail are the instrumentation, the film preparation and the first results obtained with 77:23 permalloy films. The structural investigation was carried out by using electron microscopy and electron diffraction techniques. Replicas of the surface of the films indicated the presence of foof a roughness which, at present however, has not been correlated to the magnetic uniaxial anisotropy h is the correlation of the magnetic and structural properties of thin ferromagnetic films. Described in detail are the instrumentation, the film preparation and the first results obtained with 77:23 permalloy films. The structural investigation was carried out by using electron microscopy and electron diffraction techniques. Replicas of the surface of the films indicated the presence omeasurement of the angular dependence of the torque with a sensitive torque magnetometer. The magnetic data are discussed in terms of the behavior of single domain and multi domain magnetic particles. (Author).

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 77

View

Book Description
Permalloy films evaporated at normal and oblique incidence to a substrate were examined by replication of their surfaces. Electron micrographs revealed chains of particles perpendicular to the incident beam when the angle of incidence was lesser than 70 degrees and parallel to the incident beam when the angle was greater than 70 degrees. The degree of alignment depended upon the angle of incidence and thickness of the film. Permalloy films were epitaxially grown on NaCl and were annealed by electron bombardment in an electron microscope. Perfect single crystal diffraction patterns indicated the presence of (100) parent crystals and (122) twin crystals. Fringe patterns observed on electron micrographs were identified by dark field microscopy and electron diffraction as being caused by platelets of twins 100-400 angstroms thick, lying parallel to (111) planes of the parent crystal. The non-integral reflections were shown to be caused by double diffraction.

Author: Prabandha Nakarmi
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 0

View

Book Description
Magnetic materials are of great importance for a wide range of applications from daily usage to industrial scale equipment. Different devices require different classes of magnetic materials based on the required magnetic properties. Magnetic properties of these materials are influenced by the microstructure of the material. Therefore, a detailed understanding of the microstructures of magnetic material and their influence on the magnetic properties are extremely crucial to optimize materials for particular applications. This dissertation provides theoretical and experimental studies of the influence of the microstructural properties of ferromagnetic materials on the dynamic magnetic properties using numerical simulations and ferromagnetic resonance experiments.A theoretical investigation of the influence of the magnetic properties of multiple constituents of a material on the presence of multiple resonances observed in magnetization dynamics studies is presented in the second chapter of this dissertation. In addition, this chapter also provides insights regarding the consequences of erroneous model assumptions on extraction of material parameters from studies of the magnetization dynamics. The understanding gained from the studies of the second chapter is used in chapter three to study the presence of two strong resonances in cobalt-based nanocomposites and its derivatives synthesized by addition of cobalt and boron. Furthermore, detailed structural and magnetic analyses of cobalt and boron added nanocomposites under the influence of annealing are presented in the third chapter of this dissertation. In chapter four, the influence of defects on the Gilbert damping in polycrystalline iron is investigated. Detailed ferromagnetic resonance studies of the polycrystalline iron samples showed a surprising insensitivity of the damping parameter to defects present in the samples at room temperature.

Author: ezhil arasan Manoharan
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 112

View

Book Description
Intermetallic thin films have tunable magnetic properties. The magnetic phases of intermetallic thin films were tuned by changing the alloy composition of the intermetallic system. L10 Fe50Pt50 thin film has high magnetic anisotropy which makes them ideal candidates for the thin film recording media. Magnetic phases of Fe50Pt50 can be tuned by the addition of third element like Mn by forming Fe50-x Mnx Pt50 ternary alloy system. In this work magnetic phases of ordered Fe rich Fe50-xMnxPt50 and Mn rich Fe50-xMnxPt50 thin films of Fe50-x Mnx Pt50 alloy system is investigated. Fe rich Fe50-xMnxPt50 thin films are epitaxially grown on a- Al2O3 and MgO (100) substrates, while Mn rich Fe50-xMnxPt50 thin films are grown on MgO (100) substrates. The change in the magnetic properties in Fe rich Fe50-xMnxPt50 thin films due to presence of tetragonal phase and the prediction of a the presence of a new low temperature phase in the Mn rich Fe50-xMnxPt50 thin films is verified. These intermetallic films are produced in a Ultra High Vacuum sputtering system with Reflective High Energy Electron Diffraction and Auger electron spectroscopy. RHEED is used to verify epitaxy and Auger electron spectroscopy measures chemical composition.

Author: B. J. Nicholson
Publisher:
ISBN:
Category : Alloys
Languages : en
Pages : 284

View

Book Description
This report comprises a selective survey of the present knowledge of the effects of occluded gases and strains on the magnetic properties of Permalloy films, particularlly those which have significance for computer switching applications. Other possible techniques for accomplishing future computer switching functions and magnetic film properties are reviewed. Bulk properties are described and compared with corresponding thin film properties. The magnetic properties of epitaxial Permalloy, epitaxial nickel, epitaxial iron, polycrystalline nickel, and polycrystalline iron films are discussed. The effects of various occluded gases on magnetic film properties are summarized. Stresses present in evaporated films and their significance in determining the magnetic properties of thin films are considered. A selected bibliography of 548 references is included. (Author).

Author: Matthias Wuttig
Publisher: Springer Science & Business Media
ISBN: 9783540583592
Category : Technology & Engineering
Languages : en
Pages : 400

View

Book Description
This research monograph discusses the close correlation between the magnetic and structural properties of thin films in the context of numerous examples of epitaxial metal films, while emphasis is laid on the stabilization of novel structures compared to the bulk material. Further options, possibilities, and limits for applications are given. Techniques for the characterization of thin films are addressed as well.

Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1166

View

Book Description

Author: Behrouz Khodadadi
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 105

View

Book Description
Investigating the damping processes and the behavior of dynamic magnetic properties in ferromagnetic thin films has been an important key towards design and fabrication of different microwave and magnetic recording devices. This thesis discusses the dynamic magnetic properties and also the physics behind different relaxation mechanisms in ferromagnetic thin films using comprehensive experimental investigations by means of broadband ferromagnetic resonance (FMR) technique. In chapter one the basics of ferromagnetic resonance technique and the experimental features of the FMR setup used in this study are discussed, also the FMR data analysis is explained. Chapter two is devoted to the study of the interfacial perpendicular magnetic anisotropy (PMA) and damping parameter in Co2FeAl thin films. In chapter three broadband temperature dependent FMR measurements were carried out on Ni80Fe20/Gd thin films to investigate the behavior of ferromagnetic relaxation, and gyromagnetic ratio as the system goes through the Curie temperature of Gd. In chapter four, the ferromagnetic relaxation mechanisms in ferrites are discussed. The low loss Nikel Ferrite and Lithium ferrite single crystal, thin and ultra-thin films were characterized by detailed FMR measurements to investigate the effect of microstructural defects on the magnetization relaxation. A comprehensive study on the interlayer exchange coupling strength in Co90Fe10/Ru/ Co90Fe10 multilayers is the subject of chapter five, in which the mutual spin pumping is discussed as a recently discovered channel for relaxation in exchange coupled multilayers.

Author: Jennifer Rose Soliz
Publisher:
ISBN:
Category :
Languages : en
Pages : 249

View

Book Description
Abstract: In this entire work, we characterize the structural, electrical, and magnetic properties of many novel magnetic polycrystalline materials. Our focus is to investigate these properties to enhance the scientific community and possibly pave the road to explore into other directions, such as growing thin films. we investigate the effect of charge carrier substitution with chemical disorder for Ca1-xLaxMn0.5Ru0.5O3 (x = 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, and 0.0) double perovskites. X-ray diffraction measurements showed these polycrystalline powders to be phase pure and to exhibit Pnma symmetry with a b+a- octahedral tilting. Neutron powder diffraction (NPD) showed that the crystal structure and magnetic moments do not change significantly across the substitution range. Ca0.5La0.5Mn0.5Ru0.5O3 exhibits ferrimagnetism. NPD further concluded the lack of cooperative Jahn Teller distortion. Density functional theory (DFT) calculations confirmed that the extra 1/2 electron is responsible for opening the band gap, in that 0.295e and 0.17e is being transferred to the Ru and Mn bands, respectively. Thus, the Fermi level is being tuned when La3+ is substituted into the system. DFT calculations also showed ferrimagnetism to be the most energetically stable magnetic phase. Overall we conclude that despite the chemical disorder, Ca0.5La0.5Mn0.5Ru0.5O3 is an insulating ferrimagnet with a Curie temperature (TC) of 233 K, which is a rare finding to have chemical disorder with magnetic order. The next chapter, we examine the effects of isovalent substitution in Ba1-xSrxMn0.5Ru0.5O3 system. We explore how the larger cation, Ba2+, impacts the structural, electrical, and magnetic properties. We find that BaMn0.5Ru0.5O3 crystallizes in the 9R polymorph with R-3m symmetry. BaMn0.5Ru0.5O3 is an insulating canted antiferromagnet with a TN of 36 K. From neutron diffraction, Mn1 and Mn2 have magnetic moment values of 1.60(4) uB/f.u. and 2.15(2) uB/f.u., respectively. For simplicity, the Ru moments were not refined. While the refined moments are low for Mn3+/4+, it is assumed that Ru is contributing to the magnetic moments. Ba0.5Sr0.5Mn0.5Ru0.5O3 crystallizes with the 6H crystal structure which has P63/mmc symmetry. From low temperature neutron diffraction, Ba0.5Sr0.5Mn0.5Ru0.5O3 exhibits glassy behavior since it lacks long range magnetic order. Resistivity measurements show this compound to be an insulator. In the following chapter, we continue studying Ba1-xAxMn0.5Ru0.5O3 perovskites by substituting in charge carriers. We explore the effects of aliovalent substitution, La3+, by investigating the structural, magnetic, and electrical properties for the phase diagram of Ba1 xLaxMn0.5Ru0.5O3 system. The end members were found to be phase pure solid solutions while the in between compositions were heterogeneous mixtures. While BaMn0.5Ru0.5O3 exhibits the 9R as noted above, Ba0.5La0.5Mn0.5Ru0.5O3 manifests the 3C (I4/mcm space group symmetry) crystal structure and is an insulating ferrimagnet with a TC of 205 K. From neutron diffraction, both the ferromagnetic and ferrimagnetic structures have similar refinement values. However, the moments obtained from a ferrimagnetic structure (Mn = 3.7 uB/f.u. and Ru = -0.88(2) uB/f.u.) are more reasonable than for a ferromagnetic structure (Mn = 1.707(7) uB/f.u. and Ru = 1.707(7) uB/f.u.). Plus the magnetization shows Ba0.5La0.5Mn0.5Ru0.5O3 to have 1.54 uB/f.u., which is closer in value to the expected spin only ferrimagnetic moment for Mn3+ + Ru4+ oxidation states. Thus we conclude that Ba0.5La0.5Mn0.5Ru0.5O3 is a ferrimagnet based on the refined magnetic moments gathered from neutron diffraction and the magnetization results from SQUID. Thin films of Sr2CrReO6 have been reported to be metallic (possibly half-metallic) with a high Curie temperature (635K), which makes this material a feasible candidate for spintronic applications. To understand the role of doping, investigations of the structural, electrical, and magnetic properties of on and off stoichiometric Sr2+xCrReO6 (x = -0.07, 0.0, 0.05, 0.075, and 0.10), Sr2Cr1+yRe1 yO6 (y = 0.1, 0.05, 0.05, and 0.1), and A-site substituted Sr2-zAzCrReO6 (A = K, Ca, and La; z = 0.10 and 0.20; z = 1.0 only for Ca) samples have been achieved. Varying the Cr/Re ratio and aliovalent substitutions on the A-site lead to systematic variations in the magnetization and Curie temperatures. As the Re oxidation state increases, the saturation magnetization increases and the Curie temperature decreases. In the last chapter, we investigate the structural, magnetic, and electrical properties of phase pure polycrystalline Sr2CrOsO6. From X-ray powder diffraction, Sr2CrOsO6 adopts the symmetry and is 73.6(3) % ordered. Our magnetic results show Sr2CrOsO6 to be a ferrimagnet with a small net moment of 0.224 uB/f.u. and the coercitivity to be 7.84 T at 4.5 K in a field strength of 35 T, and the Curie temperature is 660 K. Sr2CrOsO6 is strongly insulating with resistivity of 0.0861 [omega]*cm at 300 K and shows activated electron transport.

Author: A. Fert
Publisher: Elsevier
ISBN: 0444596690
Category : Technology & Engineering
Languages : en
Pages : 642

View

Book Description
Materials Research in thin and ultrathin magnetic structures is a multidisciplinary field which heavily relies on state-of-the-art growth, characterization and theoretical approaches to build a comprehensive physical picture on how magnetic properties depend on interfacial structural issues, interlayer coupling and transport phenomena. Often in this field, the critical properties and characterization required necessitates knowledge of structural and magnetic phenomena extending over several atomic planes. Atomic controlled growth techniques are required and atomic sensitivity is needed from magnetic and structural probes. This critical knowledge is vital for device applications, providing the basis for the synergistic interactions that are predominant in this field of research. This volume is the definitive reference source for anyone interested in the latest advances and results of current experimental research in ultrathin film magnetism.