Paper
“Magnetic Anisotropy Of Fine Particles” In nature, single domain particles are magnetized to saturation, where the magnetization has an easy axis, or several easy axes, along which it prefers to lie. In this case the total internal energy is minimum. Rotation of the magnetization vector away from the easy axis is possible only by applying an external magnetic field. This phenomenon is called magnetic anisotropy. Thus, the term magnetic anisotropy describe the dependence of the internal energy on the direction of magnetization of the particle. The energy term of this kind is called a magnetic anisotropy energy. Generally it has the same symmetry as the crystal structure of the particle material, and we call it a magnetocrystalline anisotropy or crystal anisotropy . This kind of anisotropy is due mainly to spin-orbit coupling . For instance, we consider an anisotropy that is uniaxial in symmetry. In this case, one of the simplest expressions of the magnetic anisotropy energy is Ea=KaVsin2 , where is the angle between the magnetization vector and the symmetry axis of the particle, V is the volume of the particle, and Ka is the anisotropy energy per unit volume or the anisotropy constant. The srength of the anisotropy in any particular crystal is measured by the magnitude of the anisotropy constants.
Consider a specimen of fine particles having no preferred orientation of its particles. If we have spherical particles, there will be no shape anisotropy, and the same applied field will magnetize it to the same extent in any direction. But if it is a nonspherical particles, the magnetization vector will not necessarily lie along an easy crystallographic axis, but rather along an axis whose demagnetizating field is a minimum. This is called shape anisotropy and was proposed by (1947).
In real systems, there is always a particle size and shape distributions as well as a distribution of particle enviroments, depending on the topology of the system (e.g. in the case of a dispersion of particles distributed in a hosting matrix). This leads to a distribution of the total energy barriers of particles, P(ED) say, because of the different values of the various contributions ( i.e. magnetocrystalline, surface, stress, shape, etc.) and thus to distributions of the blocking temperatures TB.
Другие работы по теме:
Mass Spectrometer Essay Research Paper Mass SpectrometerA
Mass Spectrometer Essay, Research Paper Mass Spectrometer A mass spectrometer produces charged particles (ions) from the chemical substances that are to be analyzed. The mass spectrometer then uses electric and magnetic fields to measure the mass (weight) of the charged particles. There are many different kinds of mass spectrometers, but all use magnetic and/or electric fields to exert forces on the charged particles produced from the chemicals to be analyzed.
Auroras Or Northern Lights Essay Research Paper
In certain polar regions of the earth, a rare and fascinating phenomenon occurs in the dark season of winter. This phenomenon is called the Northern Lights, or auroras. In areas where auroras can be seen, the sun shines brightly for six months and then disappears for the next six. The sun follows a straight path across the sky, rising in the north and setting in the south.
College Level Physics Essay Research Paper I
College Level Physics Essay, Research Paper I feel the future of transportation lies in space travel. People can go any where in the world and can do anything but travel in space. This is do to the incredible cost of space travel. The use of massive amounts of fuel for departing and re-entering the atmosphere contributes a high percentage of the cost.
Rutherford Essay Research Paper Ernest Rutherford 18711937Ernest
Rutherford Essay, Research Paper Ernest Rutherford (1871-1937) Ernest Rutherford was born in Nelson, New Zealand. Rutherford demonstrated his abilities as a scientist early on while working on his B.Sc. at the University of New Zealand in 1894. He showed that the magnetization can be removed from a magnetized iron needle by dissolving the surface layer of the metal in acid.
Pierre Curie Essay Research Paper Born in
Pierre Curie Essay, Research Paper Born in 1859 in Paris, Pierre Curie was a French physicist who spent a great deal of his life dealing in the fields of chemistry and physics. During his lifetime, he was known for his work in radioactivity, magnetism, piezoelectric effect, and his work and studies with his wife Marie Curie in discovering new elements on the periodic table.
Magnetic Fields Essay Research Paper IntroductionIn days
Magnetic Fields Essay, Research Paper Introduction: In days of old, it was a common site to see individuals peddling serums or devices that were purported to cure all your afflictions. Most of these claims were, of course, fraudulent but held a fascinating and alluring idea. Despite today?s medical milieu, and the many advances made in medical technology since those days of covered wagons and street side pharmacies, humans are still searching for some way to cure the afflictions of the human condition.
Poem Destiny Essay Research Paper Sometimes I
Poem: Destiny Essay, Research Paper Sometimes I wonder if life is just meant to be If we have not a choice in the matter, or we really are free I walked down the street on one fine day
Dalton Theory Essay Research Paper Dalton sAtomic
Dalton Theory Essay, Research Paper Dalton s Atomic Theory John Dalton developed the first useful atomic theory of matter around 1803. In the course of his studies on meteorology, Dalton concluded that evaporated water exists in air as an independent gas. Solid bodies can’t occupy the same space at the same time, but water and air could.
Korean Pollution Essay Research Paper Deadly particles
Korean Pollution Essay, Research Paper Deadly particles are circulating within our air supply. They are ?the most life threatening for of air pollution.? These are tiny particles of soot and other matter released from diesel engines in lorries, buses, and coaches. They are believed to have played a role in the premature deaths of 8,000 people.
Does God Esists Essay Research Paper DOES
Does God Esists Essay, Research Paper DOES GOD ESISTSDescription of this essay : PHILISOPY PAPERAquinas second proof that God exists, the proof from efficient cause, is summarized in the following: there exists things that are caused, nothing can be the cause of itself, there cannot be an infinite regress of causes, there fore, God exists.
Analysis Of Austin S Air Quali Essay
, Research Paper Christopher Lee Analysis of Austin s Air Quality When taking an analysis of a certain area s air quality, many different factors are taken into account. The more factors, the more accurate the analysis will be. Air quality can be measured in more than one way. The Ozone Forecast and the measure of Airborne Particulates are two factors that are considered when toxicologists analyze the air quality.
Space Exploration Essay Research Paper If the
Space Exploration Essay, Research Paper If the nation is serious about the manned exploration and development of space, then more attention must be focused now on research to study how weightlessness and reduced gravity would affect everything from power production to plumbing. The research is critical for the development of space-related technologies.
Space Storms Essay Research Paper Space StormsI
Space Storms Essay, Research Paper Space Storms I. Introduction For years, citizens in the United States have had access to televised weather as well as radar images of storm activity from around the world. Weather prediction has become increasingly accurate with the advancement of technology and should continue to get better.
Light Essay Research Paper Light is what
Light Essay, Research Paper Light is what we see. It can be thought of either as a particle, (the photon), or as a wave. The photon we can easily think of as a small dot travelling through space at the speed of light. Each photon has a particular colour or energy. But how do we think of light as a wave? For this we need to know that light is also an “Electro-magnetic field” — a combination of electric-field and magnetic-field — the same thing that causes static electricity and magnets to attract (or repel) things.
Georges Charpac Essay Research Paper Georges CharpakGeorges
Georges Charpac Essay, Research Paper Georges Charpak Georges Charpak, a French citizen, was born on August 1, 1924 in Poland. Charpak’s family moved from Poland to Paris when he was seven years old. During World War II Charpak served in the resistance and was imprisoned by Vichy authorities in 1943. In 1944 he was deported to the Nazi concentration camp at Dachau, where he remained until the camp was liberated in 1945.
Benefits Of Radiation Essay Research Paper
Benefits of Radiation Radioactivity is the spontaneous disintegration of atomic nuclei by the emission of subatomic particles called alpha particles and beta particles, or of electromagnetic rays called X rays and gamma rays. The phenomenon was discovered in 1896 by the French physicist Antoine Henri Becquerel when he observed that the element uranium can blacken a photographic plate, although separated from it by glass or black paper.
Soil And Fertilization Essay Research Paper Soil
Soil And Fertilization Essay, Research Paper Soil and Fertilization Soil is the superficial covering of most of the earth s land area. This soil is made up of minerals and organic particles produced by organic decay. The main components of soil are undissolved inorganic compounds, soluble nutrients, organic matter, water, and gases.
Magnetic Spectrum Essay Research Paper Electromagnetic SpectrumAn
Magnetic Spectrum Essay, Research Paper Electromagnetic Spectrum An electromagnetic spectrum is the spectrum in which electromagnetic waves are sent out and in which they can be detected. The spectrum of electromagnetic waves includes the following waves: microwave, radar, satellite, UHF T.V., VHF T.V., FM radio, CB radio, amateur radio, and AM radio.
Nuclear Magnetic Resonance Essay Research Paper The
Nuclear Magnetic Resonance Essay, Research Paper The measurement of nuclear and electron magnetic resonance on bulk materials was made possible by Felix Bloch and Edward Purcell and in 1952 they shared the Nobel Prize in Physics for their work. Until then, magnetic resonance was a measurable phenomena in which atoms were shot through a magnet as a beam.
Photoelectric Effect Essay Research Paper Photoelectric EffectPhotoelectric
Photoelectric Effect Essay, Research Paper Photoelectric Effect Photoelectric Effect is the formation and liberation of electrically charged particles in matter, usually metals, when it is irradiated by light or other electromagnetic radiation. The term photoelectric effect designates several types of interactions.
Modern Atom Model Essay Research Paper The
Modern Atom Model Essay, Research Paper The evolution of the modern atom model took several years to evolved with contribution from different scientists. One of these scientists, the first to come up with a modern model of the atom is JJ Thomson. Thomson proposes that the structure of an atom is mainly a sphere.
Natural Resource Essay Research Paper Natural ResourcesAs
Natural Resource Essay, Research Paper Natural Resources As the world continues to become more and more populated, resources will begin to be in demand more often. However, because of the population growth, resources will eventually become depleted. According to the food chain, food (being one of man s greatest resources) will eventually run out if there are no producers.
Nuclear Fusion Essay Research Paper Nuclear Fusion
Nuclear Fusion Essay, Research Paper Nuclear Fusion is constantly present in our solar system. In the core of the sun, Hydrogen is converted to Helium providing enough energy to sustain life on earth. This process occurs at temperatures of 10-15 million degrees Celsius.
Aurora Borealis Essay Research Paper Near the
Aurora Borealis Essay, Research Paper Near the Earth’s poles a magnificent spectacle of shimmering colored light can sometimes be seen — the aurora. The aurora is called the aurora borealis (Northern lights) and the aurora austrails (Southern lights); it can appear as bright as a full moon. The aurora usually appears near the Earth’s poles, and more northerly (or southerly) your latitude, the more impressive the displays you will see.
Facts Of Life
: “Existence Is Truth” Essay, Research Paper The Facts of Life “Existence is Truth” Everything we know of is the third dimension, and its properties. Everything is composed of atoms, and atoms are composed of smaller particles. All particles are threedimensional because they have the dimension of height, the dimension of width, and the dimension of depth.
The Gem Of Magnetic Fluids Essay Research
Paper 1.1 PRELUDE:The phenomenon of ferromagnetism is associated only with the solid state of matter; like iron, nickel, cobalt and some rare earth metals and their alloys. Thus, up to now, there is no intrinsic homogeneous fluid having ferromagnetic properties; although, theories admit the possibility of ferromagnetism in the liquid state, and suggest that there is no inherent reason why they should not exist [1-3,5].
Ratio Of Charge To Mass For The
Electron Essay, Research Paper Introduction: The object of this lab was to determine the measure of the ratio of an electron to its mass. This is done by accelerating a stream of electrons through a measured potential difference. The stream of electrons moves through a uniform magnetic field. It is perpendicular to the velocity of the electrons.
Discovery Of The Electron Essay Research Paper
The Discovery Of The Electron The electron was discovered in 1895 by J.J. Thomson in the form of cathode rays, and was the first elementary particle to be identified. The electron is the lightest known particle which