Ferromagnetic Definition and 76 Threads

Ferromagnetism is the basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets. In physics, several different types of magnetism are distinguished. Ferromagnetism (along with the similar effect ferrimagnetism) is the strongest type and is responsible for the common phenomenon of magnetism in magnets encountered in everyday life. Substances respond weakly to magnetic fields with three other types of magnetism—paramagnetism, diamagnetism, and antiferromagnetism—but the forces are usually so weak that they can be detected only by sensitive instruments in a laboratory. An everyday example of ferromagnetism is a refrigerator magnet used to hold notes on a refrigerator door. The attraction between a magnet and ferromagnetic material is "the quality of magnetism first apparent to the ancient world, and to us today".Permanent magnets (materials that can be magnetized by an external magnetic field and remain magnetized after the external field is removed) are either ferromagnetic or ferrimagnetic, as are the materials that are noticeably attracted to them. Only a few substances are ferromagnetic. The common ones are iron, cobalt, nickel and most of their alloys, and some compounds of rare earth metals.
Ferromagnetism is very important in industry and modern technology, and is the basis for many electrical and electromechanical devices such as electromagnets, electric motors, generators, transformers, and magnetic storage such as tape recorders, and hard disks, and nondestructive testing of ferrous materials.
Ferromagnetic materials can be divided into magnetically "soft" materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically "hard" materials, which do. Permanent magnets are made from "hard" ferromagnetic materials such as alnico, and ferrimagnetic materials such as ferrite that are subjected to special processing in a strong magnetic field during manufacture to align their internal microcrystalline structure, making them very hard to demagnetize. To demagnetize a saturated magnet, a certain magnetic field must be applied, and this threshold depends on coercivity of the respective material. "Hard" materials have high coercivity, whereas "soft" materials have low coercivity. The overall strength of a magnet is measured by its magnetic moment or, alternatively, the total magnetic flux it produces. The local strength of magnetism in a material is measured by its magnetization.

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  1. C

    Attraction between ferromagnetic materials in a magnetic field: what is this?

    Hello! Just so you know, I am a high school student. I am asking about this because I am an IB student and doing an extended essay (it's basically research, and a bunch of experimentation to answer a research question) on something related to magnetic fields, ferromagnetic materials, or...
  2. M

    Force on a ferromagnetic object

    How can one calculate (even as a rough estimate) the force exerted on a ferromagnetic object by a magnetic field created by a solenoid? Thanks
  3. D

    How Does Electron Spin Orbit Influence Ferromagnetic Transformer Functionality?

    I have been working on a transformer that has a potential difference out but no current. it uses of electron spin orbit to work. here is a brief explanation with some references i have uncovered that iron is unique in that each atom has a magnetic moment, that is each atom has a north...
  4. S

    Everything has ferromagnetic properties (?)

    Is it true that every material can be attracted by a magnetic field provided that the magnetic field is STRONG enough?
  5. K

    Force Exerted on Ferromagnetic Object by Permanent Magnet

    Hello everyone. There is a little project I could use some help with. I would like this done in a spreadsheet, so I can mess around with different values. The Problem: On one hand, I have a permanent magnet and, on the other, I have a ferromagnetic object. I want to find out the force...
  6. A

    Magnetic dipole moment of a ferromagnetic cylinder

    I have a Nickel cylinder, 5 micron in diameter and 10 micron in length. I know the external field \vec{B} is 80 gauss, what is the formula for the magnetic dipole moment of this cylinder in the field? Now I only have the formula for magnetic dipole of spheres, which is \mu = \frac{4}{3}\pi...
  7. S

    Magnetostatic Spin Wave: Wave Modulation in Ferromagnetic Medium

    In the context of electromagnetic wave propagation in ferromagnetic medium, what is meant by magnetostatic spin wave? This terminology one came across in the wave modulation in ferromagnetic medium. Thanks in well advance..
  8. S

    Magnetic force on ferromagnetic body

    Hello when we study electromagnetic ,it is easy to find force of a magnetic field on particle witch has electric charge (for example electron and ...) but what is force of magnetic field on ferromagnetic materials? for example if we put a cube of soft iron with a*a*a dimentions near a...
  9. U

    Magnetic field of ferromagnetic material

    I've searched high and low among the vast archives of the internet and have yet to find any kind of formula regarding the magnetic field strength of ferromagnetic material (i.e bar magnet... etc). Does anyone know what/if there is one? As is B(r)=...? Thanks
  10. E

    Is the Spin of Electrons Aligned Opposite to Net Magnetization in Ferromagnets?

    Hi everybody The bands of up- and down-spins are split in the bandstructur of a ferromagnet. Does the part with the higher amount result in a net magnetization? If yes, doesn't that mean, that electrons passing a ferromagnet, they align their spin in the opposite direction compared to the...
  11. C

    Acura's Ferromagnetic Oil: Fact or Fiction?

    I searched around the forum and found no mention of this so I figured I'd bring it up. Acura has been airing these commercials ( http://www.youtube.com/watch?v=rnZ4EyKrLAI" ) that claim to use a ferromagnetic liquid instead of oil and then claim that it improves handling. Is any of this true...
  12. B

    Ferromagnetic Pillar Calculations

    I'm doing a research project using sensors in mobile smartphones, mainly the magnetometer. After taking extensive measurements on some pillars, in a hallway, that seem to give off a high magnetic field, measured by the smartphone's magnetometer, I now want to compare these magnetic field...
  13. A

    Amorphous Ferromagnetic Metallic Alloys

    "Amorphous Ferromagnetic Metallic Alloys" Hello all, In a project in which I'm looking to endeavor, I have a need for a material with high magnetic permeability and high electrical resistivity. In beginning my research, I came across this in Wikipedia: "One can also make amorphous...
  14. R

    Why does flux flow through ferromagnetic materials?

    Can anyone help me understand why magnetic flux flows through ferromagnetic materials like an iron ring? Also, say you have a toroid with a wire wrapped around it (in air) how can you say that the flux that goes through one "loop" will go through ALL the others? These are just some things...
  15. P

    Spin glass for ferromagnetic systems

    Homework Statement hamiltonian is given by H=-\sum Jij si sj so interaction constants are Jij=EiEj and Ei=+1,-1 si=+1,-1 randomly , they are spin variables. the question is : show that this system is equivalent to a ferromagnet, by redefining the spin variables. The Attempt at a Solution...
  16. J

    Ferromagnetic Windings in Electric Motors: Can They Operate?

    Can the wire windings in an electric motor be ferromagnetic and still operate? Why?
  17. S

    Magnetic Susceptibility (Ferromagnetic)

    Homework Statement Near the critical point, Gibbs free energy of a ferromagnetic system can be written as (1). a)Using the definition of magnetization, (2), show that m(t,H=0) = Bt^{\beta} B is a constant. Determine \beta in relation to \alpha and \Delta b) Show that the...
  18. M

    Exploring Unmagnetized Ferromagnetic Materials in Magnetic Fields

    I'm wondering about general magnetic forces, specifically the behavior of unmagnetized ferromagnetic materials in a magnetic field. I.e., a simple bar or electromagnet picking up an unmagnetized piece of iron. Are there formulas to explain this behavior? The lorenz force equations by...
  19. S

    Ferromagnetic effect at smaller/larger grain size

    Hi everybody, I have faced with a problem in my report. The question said that "How can ferromagnetic effect change to depend on particle/grain size(at nm (10, 50, 100, 1000...) and at \mum (0.5, 1, 2...)?" (In shortly, what can we observe at feromagnetic effect if we increase and decrease of...
  20. I

    Can a Ferromagnetic Material Be Demagnetized?

    once a ferromagnetic material is magnetized, does it ever go back to it's original "randome magnetic moment" state?
  21. T

    How can I calculate the energy needed for ferromagnetic hysteresis?

    Homework Statement It's a past paper question, but I just don't understand it. I must have missed something here... Homework Equations Maxwell's equations, \frac{B}{\mu_{0}} = H + M, M=\chi H change in stored energy = H.dB The Attempt at a Solution (a) \nabla\times H =...
  22. A

    Ferromagnetic dipole in a uniform magnetic field

    a- I place a ferromagnetic dipole in a uniform magnetic field so that the axis of the dipole moment vector does not lie parallel to the magnetic field lines. Is there a net force on the dipole? Is there a net force? b- I place a ferromagnetic dipole in a uniform magnetic field so that the axis...
  23. S

    Two ferromagnetic balls, rolling down a ruler

    Here's the situation: We have a ruler, inclined slightly with a strong ceramic magnet at the end. Now, we put two identical ferromagnetic (steel, for example) balls on the top of the ramp, touching each other. We let the balls roll down the ramp, and, perhaps against intuition, the balls...
  24. Z

    How Do Paramagnetic and Ferromagnetic Materials Differ in Magnetic Fields?

    What is the difference between paramagnetic materials and their behaviour in magnetic fields?? Thanks a lot for the help...having a magnetism test 2 days from now:frown:
  25. K

    Band structure of ferromagnetic metal

    for a ferromagnetic metal, the there will be splitting of energy band(one for spin up e- and one for spin down e-) under the influence of external magnetic field. the it is known as exchange splitting. here are my questions 1. what determine the degree of splitting? i guess it depends on the...
  26. O

    The Magnetic Properties of a Single Ferromagnetic Atom

    Can a single atom of a ferromagnetic material display properties of ferromagnetism? In other words, is an iron atom affected by magnetic fields the same way a chunk of iron is? In other other words, does a single atom of a ferromagnetic material still have a net magnetic dipole moment, or is...
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