scholarly journals The Influence of Thickness on the Magnetic Properties of Nanocrystalline Thin Films: A Computational Approach

Computation ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 45
Author(s):  
Jose Darío Agudelo-Giraldo ◽  
Francy Nelly Jiménez-García ◽  
Elisabeth Restrepo-Parra
Keyword(s):  
Thin Films ◽  
Zeeman Effect ◽  
Three Dimensional ◽  
Great Influence ◽  
Dipolar Interaction ◽  
Magnetic Behaviour ◽  
Blocking Temperature ◽  
Surface Anisotropy ◽  
Polycrystalline Thin Films ◽  
Plane Anisotropy

A study of the magnetic behaviour of polycrystalline thin films as a function of their thickness is presented in this work. The grain volume was kept approximately constant in the virtual samples. The model includes the exchange interaction, magneto-crystalline anisotropy, surface anisotropy, boundary grain anisotropy, dipolar interaction, and Zeeman effect. The thickness-dependence of the critical temperature, blocking temperature, and irreversibility temperature are presented. Surface anisotropy exerts a great influence at very low thicknesses, producing a monodomain regime. As the thickness increases, the dipolar interaction produces a coupling in-plane of single domains per grain which favours superparamagnetic states. At higher thicknesses, the effects of the in-plane anisotropy produced by dipolar interaction and surface anisotropy decrease dramatically. As a result, the superparamagnetic states present three-dimensional local anisotropies by the grain.

EFFECTS OF THE DIPOLAR INTERACTION ON THE MAGNETIC PROPERTIES OF NANOPARTICLES ARRANGED IN DIFFERENT LATTICE SYMMETRIES

2012 ◽  
Vol 23 (08) ◽  
pp. 1240006 ◽  
Author(s):  
ANTONIO WEIZENMANN ◽  
WAGNER FIGUEIREDO
Keyword(s):  
Dipolar Coupling ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Uniaxial Anisotropy ◽  
Dipolar Interaction ◽  
Blocking Temperature ◽  
Face Centered Cubic ◽  
Easy Magnetization ◽  
Cubic Lattice ◽  
Face Centered

A set of single domain particles has been studied through Monte Carlo simulations on three different lattices. A simple cubic lattice, a face centered cubic lattice and a liquid-like structure. The particles are coupled by long-range dipolar forces and present a single ion uniaxial anisotropy, whose magnitude is chosen from a Gaussian distribution, and whose easy magnetization axes are oriented randomly in the three-dimensional space. We determined the blocking temperature and the hysteresis curves as a function of the ratio between the magnitude of dipolar coupling and uniaxial anisotropy. We show that the remanence and coercive field depend strongly on the nature of the magnetic arrangement. These results are compared with those found for a system of noninteracting particles.

Large-scale phase-field simulation of three-dimensional isotropic grain growth in polycrystalline thin films

2019 ◽  
Vol 27 (5) ◽  
pp. 054003 ◽  
Author(s):  
Eisuke Miyoshi ◽  
Tomohiro Takaki ◽  
Munekazu Ohno ◽  
Yasushi Shibuta ◽  
Shinji Sakane ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Phase Field ◽  
Large Scale ◽  
Three Dimensional ◽  
Phase Field Simulation ◽  
Field Simulation ◽  
Polycrystalline Thin Films

scholarly journals The Influence of Pressure on the Formation of FM/AF Configurations in LSMO Films: A Monte Carlo Approach

Computation ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 93
Author(s):  
Hugo Hernán Ortiz-Álvarez ◽  
Francy Nelly Jiménez-García ◽  
Carolina Márquez-Narváez ◽  
José Dario Agudelo-Giraldo ◽  
Elisabeth Restrepo-Parra
Keyword(s):  
Thin Films ◽  
Monte Carlo ◽  
Magnetic Properties ◽  
Critical Temperature ◽  
Curie Temperature ◽  
Monte Carlo Simulations ◽  
Room Temperature ◽  
Zeeman Effect ◽  
Dipolar Interaction ◽  
External Pressure

In this work, Monte Carlo simulations of magnetic properties of thin films, including the influence of an external pressure, are presented. These simulations were developed using a Hamiltonian composed by terms that represent the exchange interaction, dipolar interaction, Zeeman effect, monocrystalline anisotropy, and pressure influence. The term that represents the pressure influence on the magnetic properties was included, since for many applications, magnetic materials are a part of a multiferroic material together with a piezoelectric or a ferroelectric compound. Initially, the model was developed using generic parameters, in order to probe its suitable performance; after that, parameters were adjusted for simulating thin films of La0.67Sr0.33MnO3, a manganite with several technological applications because its Curie temperature is greater than room temperature. Including the pressure influence, it was observed the formation of several kind of FM/AF configurations as strip, labyrinth, and chess board forms. Furthermore, it was observed that, as the pressure increased, the critical temperature tended to decrease, and this result was in agreement with experimental reports.

Atomistic Monte Carlo simulations of three-dimensional polycrystalline thin films

2003 ◽  
Vol 94 (1) ◽  
pp. 163-168 ◽  
Author(s):  
J. Emiliano Rubio ◽  
Martin Jaraiz ◽  
Ignacio Martin-Bragado ◽  
Jesus M. Hernandez-Mangas ◽  
Juan Barbolla ◽  
...  
Keyword(s):  
Thin Films ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Three Dimensional ◽  
Polycrystalline Thin Films

Electron diffraction studies of amorphous and polycrystalline thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 118-119
Author(s):  
D J H Cockayne ◽  
D R McKenzie
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Polycrystalline Materials ◽  
Good Resolution ◽  
Scattered Intensity ◽  
Radial Density ◽  
X Ray ◽  
Polycrystalline Thin Films ◽  
Nitrogen Ion ◽  
Diffraction Patterns

The study of amorphous and polycrystalline materials by obtaining radial density functions G(r) from X-ray or neutron diffraction patterns is a well-developed technique. We have developed a method for carrying out the same technique using electron diffraction in a standard TEM. It has the advantage that studies can be made of thin films, and on regions of specimen too small for X-ray and neutron studies. As well, it can be used to obtain nearest neighbour distances and coordination numbers from the same region of specimen from which HREM, EDS and EELS data is obtained.The reduction of the scattered intensity I(s) (s = 2sinθ/λ ) to the radial density function, G(r), assumes single and elastic scattering. For good resolution in r, data must be collected to high s. Previous work in this field includes pioneering experiments by Grigson and by Graczyk and Moss. In our work, the electron diffraction pattern from an amorphous or polycrystalline thin film is scanned across the entrance aperture to a PEELS fitted to a conventional TEM, using a ramp applied to the post specimen scan coils. The elastically scattered intensity I(s) is obtained by selecting the elastically scattered electrons with the PEELS, and collecting directly into the MCA. Figure 1 shows examples of I(s) collected from two thin ZrN films, one polycrystalline and one amorphous, prepared by evaporation while under nitrogen ion bombardment.

RANDOM SURFACE ANISOTROPY AND THE MAGNETIZATION OF EPITAXIALLY GROWN THIN FILMS

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-1695-C8-1696 ◽  
Author(s):  
J. R. Cullen ◽  
K. B. Hathaway
Keyword(s):  
Thin Films ◽  
Surface Anisotropy ◽  
Random Surface

Electrical and photoelectrical characterization of GaAsxSy polycrystalline thin films

1997 ◽  
Vol 296 (1-2) ◽  
pp. 114-117 ◽  
Author(s):  
O. Pesty ◽  
P. Canet ◽  
F. Lalande ◽  
H. Carchano ◽  
D. Lollman
Keyword(s):  
Thin Films ◽  
Polycrystalline Thin Films

Advances in coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery

2020 ◽  
pp. 095441002096645
Author(s):  
Jie Gao ◽  
Chunde Tao ◽  
Dongchen Huo ◽  
Guojie Wang
Keyword(s):  
Performance Improvement ◽  
High Efficiency ◽  
Three Dimensional ◽  
Great Influence ◽  
Aerodynamic Characteristics ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Axial Turbine ◽  
Flow Interactions ◽  
And Performance

Marine, industrial, turboprop and turboshaft gas turbine engines use nonaxisymmetric exhaust volutes for flow diffusion and pressure recovery. These processes result in a three-dimensional complex turbulent flow in the exhaust volute. The flows in the axial turbine and nonaxisymmetric exhaust volute are closely coupled and inherently unsteady, and they have a great influence on the turbine and exhaust aerodynamic characteristics. Therefore, it is very necessary to carry out research on coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics, so as to provide reference for the high-efficiency turbine-volute designs. This paper summarizes and analyzes the recent advances in the field of coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery. This review covers the following topics that are important for turbine and volute coupled designs: (1) flow and loss characteristics of nonaxisymmetric exhaust volutes, (2) flow interactions between axial turbine and nonaxisymmetric exhaust volute, (3) improvement of turbine and volute performance within spatial limitations and (4) research methods of coupled turbine and exhaust volute aerodynamics. The emphasis is placed on the turbine-volute interactions and performance improvement. We also present our own insights regarding the current research trends and the prospects for future developments.

Experimental investigation on the three-dimensional flow field from a meltblowing slot die

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 724-732
Author(s):  
Changchun Ji ◽  
Yudong Wang
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Great Influence ◽  
Distribution Characteristics ◽  
Air Velocity ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Airflow Distribution ◽  
Slot Die ◽  
Center Area

AbstractTo investigate the distribution characteristics of the three-dimensional flow field under the slot die, an online measurement of the airflow velocity was performed using a hot wire anemometer. The experimental results show that the air-slot end faces have a great influence on the airflow distribution in its vicinity. Compared with the air velocity in the center area, the velocity below the slot end face is much lower. The distribution characteristics of the three-dimensional flow field under the slot die would cause the fibers at different positions to bear inconsistent air force. The air velocity of the spinning centerline is higher than that around it, which is more conducive to fiber diameter attenuation. The violent fluctuation of the instantaneous velocity of the airflow could easily cause the meltblowing fiber to whip in the area close to the die.

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