Microstructural and Magnetic Characterization of CoPt and FePt Thin Films PDF Download
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Author: Roger A. Ristau Publisher: ISBN: Category : Iron alloys Languages : en Pages : 362
Book Description
The microstructure of sputtered, 10 nm thin films of equiatomic binary alloys of CoPt and FePt were characterized using transmission electron microscopy (TEM) and related techniques, and the magnetic properties of these films were studied using a superconducting quantum interference device (SQUID) magnetometer. These films have certain properties important to their possible application as high density magnetic storage media, however the relationship of microstructure and magnetic properties was not well known. Grain growth kinetics were examined using manual and digital analysis of bright field TEM images, and were seen to take two stages during annealing in these films. A rapid growth stage concurrent with the formation of a (111) fiber texture was observed to occur within the first 5-10 minutes of annealing, which was followed by a much slower growth stage after the fiber texturing was well advanced. Differences in grain growth rate and ultimate grain size were also observed to depend on heating rate. The transformation from an atomically disordered structure to the L1$\sb0$ ordered structure also occurred during annealing and was characterized using digital analysis of dark field TEM images. The transformation was observed to follow first-order, nucleation and growth kinetics and the volume fraction transformed was quantified for numerous intermediate steps between disordered and fully ordered. The ordered volume fraction was then compared to the magnetic coercivity data obtained from the SQUID magnetometer. In contrast to the relationship most commonly described in the literature, that the highest coercivity corresponds to a two phase ordered/disordered mixture, the maximum value for coercivity in our samples was found to correspond to the fully ordered state. Furthermore, measurements of the ordered volume fraction at intermediate steps between disordered and fully ordered showed that the coercivity was closely related to the ordered volume fraction. An increasing density of magnetic domain wall pinning sites concurrent with the increasing ordered fraction was proposed as a mechanism for the high coercivity in these films.
Author: Roger A. Ristau Publisher: ISBN: Category : Iron alloys Languages : en Pages : 362
Book Description
The microstructure of sputtered, 10 nm thin films of equiatomic binary alloys of CoPt and FePt were characterized using transmission electron microscopy (TEM) and related techniques, and the magnetic properties of these films were studied using a superconducting quantum interference device (SQUID) magnetometer. These films have certain properties important to their possible application as high density magnetic storage media, however the relationship of microstructure and magnetic properties was not well known. Grain growth kinetics were examined using manual and digital analysis of bright field TEM images, and were seen to take two stages during annealing in these films. A rapid growth stage concurrent with the formation of a (111) fiber texture was observed to occur within the first 5-10 minutes of annealing, which was followed by a much slower growth stage after the fiber texturing was well advanced. Differences in grain growth rate and ultimate grain size were also observed to depend on heating rate. The transformation from an atomically disordered structure to the L1$\sb0$ ordered structure also occurred during annealing and was characterized using digital analysis of dark field TEM images. The transformation was observed to follow first-order, nucleation and growth kinetics and the volume fraction transformed was quantified for numerous intermediate steps between disordered and fully ordered. The ordered volume fraction was then compared to the magnetic coercivity data obtained from the SQUID magnetometer. In contrast to the relationship most commonly described in the literature, that the highest coercivity corresponds to a two phase ordered/disordered mixture, the maximum value for coercivity in our samples was found to correspond to the fully ordered state. Furthermore, measurements of the ordered volume fraction at intermediate steps between disordered and fully ordered showed that the coercivity was closely related to the ordered volume fraction. An increasing density of magnetic domain wall pinning sites concurrent with the increasing ordered fraction was proposed as a mechanism for the high coercivity in these films.
Author: Sudipta Seal Publisher: Springer Science & Business Media ISBN: 0387488057 Category : Technology & Engineering Languages : en Pages : 607
Book Description
This is the first book about functional nanostructures. Nanocrystalline materials exhibit outstanding properties and represent a new class of structural materials having a wide range of applications. In particular, there is considerable interest in developing nanocrystalline materials to be used as functional materials in aerospace applications, automotive industry, wear applications, etc. Future progress in these high technological applications of nanocrystalline materials depends on development of new methods of their fabrication and understanding of the underlying nano-scale and interface effects causing their unique mechanical properties.
Author: D. Y. Oh Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
The CoPt-20at.%C thin films of 20nm thickness were sputter-deposited in the form of CoPt/C(n) (n=1: carbon layer thickness=4nm; n=4: each carbon layer thickness=1nm) and were transformation-annealed at 650 degrees C for various times. Carbon was found to dissolve into CoPt lattice and enlarge the c/a ratio of the ordered CoPt lattice. The amount of carbon dissolution increases with the decreasing carbon layer thickness at a given total carbon concentration. The carbon dissolution larger than a critical amount can lead to a shift of the phase equilibrium of ordering and produce a stable fine two-phase mixture of ordered and disordered phases at the equi-atomic composition of Co:Pt. This results in a fine and uniform stagnant grain structure of about 20nm on annealing at 650 degrees C. The carbon dissolution by increasing the c/a ratio of the ordered CoPt lattice reduces both the saturation magnetization and the magnetocrystalline anisotropy constant of the film and leads to a reduction of coercivity of CoPt films.
Author: Katayun Barmak Publisher: Woodhead Publishing ISBN: 085709629X Category : Technology & Engineering Languages : en Pages : 671
Book Description
Metallic films play an important role in modern technologies such as integrated circuits, information storage, displays, sensors, and coatings. Metallic Films for Electronic, Optical and Magnetic Applications reviews the structure, processing and properties of metallic films. Part one explores the structure of metallic films using characterization methods such as x-ray diffraction and transmission electron microscopy. This part also encompasses the processing of metallic films, including structure formation during deposition and post-deposition reactions and phase transformations. Chapters in part two focus on the properties of metallic films, including mechanical, electrical, magnetic, optical, and thermal properties. Metallic Films for Electronic, Optical and Magnetic Applications is a technical resource for electronics components manufacturers, scientists, and engineers working in the semiconductor industry, product developers of sensors, displays, and other optoelectronic devices, and academics working in the field. - Explores the structure of metallic films using characterization methods such as x-ray diffraction and transmission electron microscopy - Discusses processing of metallic films, including structure formation during deposition and post-deposition reactions and phase transformations - Focuses on the properties of metallic films, including mechanical, electrical, magnetic, optical, and thermal properties
Author: Roger A. Ristau
Author: Roger A. Ristau
Author: Yang Fu
Author: Sudipta Seal
Author: Sangki Jeong
Author: 
Author: Patrick W. DeHaven
Author: D. Y. Oh
Author: 
Author: Katayun Barmak
Author: Yukiko Kubota