Questions tagged [ferromagnetism]
The basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets. Ferromagnetism manifests itself in the fact that a small externally imposed magnetic field can cause the magnetic domains to align and reinforce with each other, so that the material is said to be magnetized.
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Why Curie temperature is bigger for smaller lattice in 2D Ising model
Using Metropolis algorithm, Curie temperature was calculated for square lattices with different sizes 4x4, 8x8, 16x16 and 32x32. Here Curie temperature was estimated as temperature of maximum of heat ...
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Heisenberg ferromagnet model
I am studying some things related to the two-dimensional $xy$ model and ended up relying on the Heisenberg model to describe a ferromagnet in the presence of an external magnetic field.
\begin{...
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How can a mean-field hubbard model describe itinerant ferromagnetism?
I see some textbooks showing how Hubbard model with Mean field approximation can explain ferromagnetism of band electrons(stoner theory), but intuitively I can't understand why an on-site Hubbard ...
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Calculation of the electrical resistance of an anisotropic conductor with spacially varying current density [closed]
Fist time posting here, so I apologize in advance for the terrible editing .
I am trying to figure out a way to calculate the total resistance of a rectangular structure with known spatially dependent ...
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Ising model and the axiomatics of Statistical Mechanics
I am revisiting Statistical Mechanics to better understand models of spin glass and was wondering to what extent axiomatics of Stat.Mech. applies to an ensamble of spin configurations. In particular, ...
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Do the random-bond Ising model correlation functions decay with the disorder strength?
I'm imagining a square lattice with Ising spins on the vertices and nearest-neighbor Ising interactions. The interaction on a given bond is ferromagnetic with probability $(1-p)$ and antiferromagnetic ...
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What is the relationship between the distance of a current carrying wire and a dipole magnet's magnetic field strength?
For school, I'm doing this experiment where I measure the change in magnetic field strength, between a magnet and a current-carrying wire as a function of the distance. Online after doing some reading,...
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Attraction/repulsion forces between two magnets
If I have two identical magnets of equal strengths producing equal repulsive forces between them, and if I replace one of the magnets with a stronger magnet (everything else remaining the same), how ...
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Ground state of the Heisenberg XXX model with a coupling?
I have a one-dimensional Heisenberg chain with a Magnetic field with $N$ sites with $J>0$
\begin{equation}
\mathcal{H} = -J \sum_{i = 1}^{N-1} \vec{S_i}\cdot \vec{S_{i+1}}- \sum_{i = 1}^N \vec{H}\...
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How to interpret Magnetic Susceptibility as the ratio of two vectors $M$ and $H$, as division of two vectors is not defined in mathematics?
Magnetic Susceptibility, denoted as χ is defined as a scalar, represents the ratio between the Magnetization vector ($\vec {M}$) and the Magnetic field strength vector ($\vec{H}$).
However, in ...
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Why does a magnet not move in presence of an electric field?
I only recently thought about this, and I can't come to any conclusion. An explanation for ferromagnets is perhaps explainable, and my teacher said Quantum Mechanics complicates things since the ...
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Rotation of spin orbit coupling matrix
In first-principle calculation, we could get different solutions for different directions of magnetization for ferromagnetic system.
I want to know the details about whether or when does the SOC ...
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What is the meaning of aligned and anti-aligned spin states in quantum mechanics?
For a quantum system of two spin-1/2 particles, the spins are said to be aligned or parallel and anti-aligned or anti-parallel, if total $S=1$ (maximum value) and $S=0$ (minimum value) respectively, ...
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Use of Curie law in Antiferromagnetic Weiss theory derivation
When deriving the magnetic susceptibility of an antiferromagnetic (AFM) material Coey in the book Magnetism and Magnetic Materials (p.196) assumes that for one sublattice it holds true that $\chi = \...
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Is the Ising magnet relevant for magnets?
To what extent is the Ising model for the ferromagnetic transition experimentally relevant for real ferromagnets ?
For example if one quantitatively compares the magnetization versus temprature data ...
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Breaking a magnet
When a bar magnet is broken into 2 pieces, we know that the 2 new pieces also become bar magnets with 2 poles. The piece corresponding to the north pole of the unbroken magnet gets a new south pole, ...
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How is the local magnetic moment determined experimentally?
The Anderson model is contrived to explain the existence/nonexistence of local magnetic moments in metallic solutions.
It is said that for a solution of A atoms in B metal, sometimes there are local ...
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Is heat treatment the only means known to man for increasing grain size in steel?
It is well known that steel grains tend to grow larger under heat treatment. Is it possible to enlarge grain size through any other means?
I cannot seem to find anything via web search. If steel is ...
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Peierl's argument for 1D Ising model
I'm having a hard time understanding Peierl's argument for the non-existence of spontaneous magnetization in a 1D Ising model at $T>0$. Let the Hamiltonian be
$$ H = -J\sum_{i} S_i S_{i+1}.$$
The ...
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Metals and Magnets
A metal is attracted by a magnet when placed in it's vicinity. I was wondering if it is the metal that moves towards the magnet, or is it that both the metal and magnet move towards each other? Could ...
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Explanation of massive Goldstone modes
I'm solving this exercise with a Heisenberg Hamiltonean in linear spin-wave theory and at some point we are asked to compute the dispersion relation at $k=0$, which leads me to finding two different ...
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How do I deal with linear terms in an ferromagnetic exchange interaction Hamiltonian?
I am currently working on deriving the dispersion relation of spin waves in a ferromagnetic monolayer, using the Holstein-Primakoff formalism. Regardless of the specifics, in my derivation I am ...
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Fresnel coefficients with permanent magnetism
I am familiar with the standard derivation of the Fresnel coefficients for linear magneto-dielectrics (for instance https://en.wikipedia.org/wiki/Fresnel_equations#Derivation). However, I was ...
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How can localized ferromagnetism (non-itinerant ferromagnetism ) exist at all?
Localized ferromagnetism refers to materials where the magnetic moments are primarily associated with localized atomic orbitals.
Ferromagnets, such as those made of iron or nickel, are called ...
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Anti-Iron property of material
Hello I've been seeing it on the YouTube, but there is not a single information on how it happens.
Those who have uploaded the videos call it "anti-iron". Appearntly it's a property of the ...
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Understanding the Landau–Lifshitz–Gilbert (LLG) equation discrepancy in literature
Background, I am a masters student in microelectronics trying to perform some micromagnetic studies.
In some literature, the $\gamma$ in the LLG equation is said to be just the gyromagnetic ratio of ...
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Mixed Spin-Glass/Ferromagnetic phase in Sherrington-Kirkpatrick (SK) model
I'm studying the Sherrington-Kirkpatrick model in the book of Nishimori Statistical Physics of Spin Glasses and Information Processing, in particular the SK model and its phase diagram. I report here ...
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Classical dipole-dipole interaction in iron
I've been reading about the classical magnetic dipole-dipole interaction and I'm wondering how it would work in a ferromagnet element like iron (theoretically under the assumptions I will write below)....
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Regarding 3D Metal Printing: Can magnetic or electrical fields affect density, form or crystallization?
Good day,
I am curious in regards to 3D metal printing. Can magnetic or electrical fields affect density, form or crystallization form in molten metals? I am interested in fine tuning the precision of ...
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Once the rotor reaches saturation in a linear motor, do further increases in B increase acceleration?
I need to accelerate a chunk of steel with a solenoid.
I calculated the B field in the bore of the solenoid, and it is > 3 T.
Most definitions of saturation place the saturation of steel around 1.5 ...
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What is difference between Ferroelectric Tunneling Junctions (FTJs) and Ferroelectric capacitors (FeCaps)?
Aren't Ferroelectric Tunneling Junctions (FTJs) and Ferroelectric capacitors (FeCaps) just ferroelectric materials sandwiched between 2 metal electrodes, with only difference being in the thickness of ...
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Time-scale of demagnetization of permanent magnets due to external field
I wonder what the time scale to demagnetize a fully magnetized permanent magnet with an external magnetic field is. The temperature is assumed to be constant.
I found a reference 1 for specific cases, ...
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Barrier layer photovoltaic effect (BLPVE) and Bulk photovoltaic effect (BPVE)
Ferroelectric materials typically exhibit the bulk photovoltaic effect (BPVE). My question is that if a material taken as an absorber in a device which works on barrier layer photovoltaic effect (...
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Relation of ferroelectric nature and electronic properties
Does ferroelectricity bring about a change in the bandgap of materials? If yes, is it due to the Stark effect causing energy splitting or any other phenomenon taking place?
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How to solve Landau-Lifshitz equation?
In the macroscopic limit, spin oscillations are described by spin waves or magnetization waves. Often a formula given is Landau-Lifshitz equation:
$$\frac{\partial \mathbf M}{\partial t}= -\gamma\...
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Spin polarization, ferromagnetism, and size of energy gap
I thought large band gap (larger than relevant spin-spin interaction energy scale) necessarily means there is no spin-polarization (ie, not ferromagnetic). I thought the reason is that {only when ...
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What is the difference between paramagnetic and ferromagnetic?
What is the difference between paramagnetism and ferromagnetism?
Before answering, I want to note my difference between the rest of the similar questions on this website: from what I think I know, ...
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Why the superexchange interaction is antiferromagnetically favorable?
From Stephen Blundell's book 'Magnetism in Condensed Matter', the superexchange interaction between two magnetic ions mediated by non-magnetic ions is generally antiferromagnetic. In his book, he ...
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What is the real cause for a demagnetizing field to exist?
In ferromagnetic context I've read many textbooks that mention "magnetic charges". From what I understood, there is no such thing as ’ magnetic charges’, however, although the notion is ...
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Field lines of two bar magnets becoming one bar magnet
I have the following conceptual missunderstanding (pressumably). If you have two bar magnets opposing each other separately, then the field lines go from the north- to the southpole of one bar to the ...
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Metropolis Monte-Carlo for magnetic system with $S > 1/2$ or arbitrary set of quantum systems
A well-known example of classical Monte-Carlo method application is Ising model with $S=1/2$.
As I understood, people there widely use it for any kind of magnetic materials following the same idea
$$
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What force causes a change in a domain's direction?
I have read that to make a material paramagnetic you can place a strong magnet next to it. How does this magnet align the domains inside the other material?
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Does there exist a ferromagnetic spin system with all ground states entangled?
Is there a lattice Hamiltonian of quantum spins $H_{\rm goal}(\vec{h})= H_{\rm goal}(\vec{0}) - \sum_i \vec{h} \cdot \vec{S}_i$ satisfying the following two conditions as the number of spins $N$ tends ...
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What is the difference between demagnetizing tensor vs demagnetizing factor
I know the first one is a tensor that basically shows components and the second is a scalar. Problem is some references call factor to the tensor and others call demagnetizing factor to the components ...
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Is the property of magnetism due to movement of electrons about a central nucleus or due to the spinning of electron about its own axis?
Look my teacher said that it's due to the movement about the nucleus.
But there are two problems in this acc to me
1.) Motion of an electron is not AT ALL circular.
2.)When we check whether an element ...
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What do Fe, Co, Ni - and possibly Gd - have in common to cause ferromagnetism and why is it seemingly absent in all other elements?
I wonder whether the causes of ferromagnetism can be located purely in the electron shells and in cristaline structure or whether there is any aspect of it that is rooted in specific properties of the ...
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Cleaning silt off magnets
I gone done a foolish thing; I got my set of spherical (⌀ 5 mm) neodymium magnets covered in of (what is presumably iron based) ferromagnetic silt/sand particles.
With some difficulty, I've been able ...
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How do I find the BH curve from the frequency-complex permeability relationship?
I come here after a lot (I mean a lot) of research about complex permeability. I have a ferrite datasheet which give the complex permeability ($\mu'$ and $\mu''$) over frequency. I don't know how to ...
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Temperature and remanent magnetization
Is it necessary or required to take into account the temperature of the environment whilst determining the remanent field $B_r$ of a magnet? According to the datasheet of the magnet $B_r$ is somewhere ...
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Relating energy density between anisotropy field and Stoner-Wohlfarth model
At this point I'm not sure if there is a jump in the text or there is a gap in my understanding.
Here goes:
Consider a uniaxial single domain crystal in which the magnetisation direction for the ...
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