What is Paramagnetism: Definition and 34 Discussions
Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, diamagnetic materials are repelled by magnetic fields and form induced magnetic fields in the direction opposite to that of the applied magnetic field. Paramagnetic materials include most chemical elements and some compounds; they have a relative magnetic permeability slightly greater than 1 (i.e., a small positive magnetic susceptibility) and hence are attracted to magnetic fields. The magnetic moment induced by the applied field is linear in the field strength and rather weak. It typically requires a sensitive analytical balance to detect the effect and modern measurements on paramagnetic materials are often conducted with a SQUID magnetometer.
Paramagnetism is due to the presence of unpaired electrons in the material, so most atoms with incompletely filled atomic orbitals are paramagnetic, although exceptions such as copper exist. Due to their spin, unpaired electrons have a magnetic dipole moment and act like tiny magnets. An external magnetic field causes the electrons' spins to align parallel to the field, causing a net attraction. Paramagnetic materials include aluminium, oxygen, titanium, and iron oxide (FeO). Therefore, a simple rule of thumb is used in chemistry to determine whether a particle (atom, ion, or molecule) is paramagnetic or diamagnetic: if all electrons in the particle are paired, then the substance made of this particle is diamagnetic; if it has unpaired electrons, then the substance is paramagnetic.
Unlike ferromagnets, paramagnets do not retain any magnetization in the absence of an externally applied magnetic field because thermal motion randomizes the spin orientations. (Some paramagnetic materials retain spin disorder even at absolute zero, meaning they are paramagnetic in the ground state, i.e. in the absence of thermal motion.) Thus the total magnetization drops to zero when the applied field is removed. Even in the presence of the field there is only a small induced magnetization because only a small fraction of the spins will be oriented by the field. This fraction is proportional to the field strength and this explains the linear dependency. The attraction experienced by ferromagnetic materials is non-linear and much stronger, so that it is easily observed, for instance, in the attraction between a refrigerator magnet and the iron of the refrigerator itself.
Hello,
I have a question regarding the limitations of Electron Spin Resonance (ESR). I've read somewhere that ESR cannot detect radicals with short lifetimes.
I'm trying to understand why is that?
For example: a highly dynamic system like liquid sulfur at high temperatures, where sulfur...
As we know, dipole can be only arranged either parallel or anti-parallel with respect to applied magnetic field ## \vec{H} ## if we are to use quantum mechanical description, then parallel magnetic dipoles will have energy ## \mu H ## and anti-parallel magnetic dipoles have energy ## -\mu H##...
I was reading the *Statistical Physics An Introductory Course* by Daniel J.Amit and need some help to understand a certain passage:
In an isolated composite system of two paramagnetic system:
System a with ##N_a## spins and a magnetic field ##H_a ##
System b with ##N_b## spins and a...
I was reading the statistical physics textbook and was really confused with the notation:
I don't understand the last part of the section. Why is that \sum_{\sigma = \pm1} \sigma P(\sigma) equals to \left< \sigma \right>? And what does \left< \sigma \right> actually mean? Is it the average...
Homework Statement
Consider a system with N sites and N particles with magnetic moment m. Each site can be in one of three states: empty with energy 0, occupied by one particle with energy 0 (in the absent of magnetic field) or occupied by two particles with anti parallel moments and energy ε...
Homework Statement
We are given a paramagnetic system of N distinguishable particles with 1/2 spin where we use N variables
s_k each binary with possible values of ±1 where the total energy of the system is known as:
\epsilon(s) = -\mu H \sum_{k=1}^{N} s_k where \mu is the magnetic moment...
I am studying some solid state physics, in particular magnetism; I have a few questions about the explanations.
My understanding is that paramagnetism is primarily an effect of the electron's spin-angular momentum: an unpaired electron will have a dipole moment which preferentially aligns with...
Hello all, new here but plan to stick around for a while. I am currently trying to make a sensor that can detect if a material below it is paramagnetic. I believe paramagnetic is the proper term, but it needs to detect if the force exerted by permanent magnet is above a certain threshold. The...
Paramagnetism: How does having an unpaired electron attract it into a magnetic field. Why not repel? Is there any reason or we just know from experiment?
Diamagnetism: If the electron spins and therefore magnetic fields cancel, what is causing it to repel from a magnetic field? If it is...
Hi,
I am working on an experiment to investigate the effect of electrical conductivity of the metals on the levitating force produced.
Basically the concept is this: when a metal plate is placed on top of a solenoid (but not touching), as the a.c. flows in the solenoid the change in magnetic...
Hello, I've been having some trouble with a paramagnetism problem from my Statistical Mechanics class textbook (F. Mandl, Statistical Physics, 2nd edition, p. 25). The problem is as follows
1. Homework Statement
2. Homework Equations
1. The temperature parameter
\displaystyle{ \beta =...
Homework Statement
(a) Show the curie-weiss behaviour.
(b) Estimate ##\lambda## and ##B_e## and exchange energy.[/B]
Homework EquationsThe Attempt at a Solution
Part(a)
Since even when applied field is zero, ##B_{total} \neq 0## which gives rise to ##M\neq 0##. This is a fundamental...
Homework Statement
Assuming 2s-2p mixing is not operative, the paramagnetic species among the following is
1. Be2
2. B2
3. C2
4. N2
Homework Equations
NA
The Attempt at a Solution
Not able to understand the statement "2s -2p mixing is not operative".
Can you help?
Paramagnetism is a specie...
Please confirm & answer the following:
An atom exposed to an external B-field will experience both a torque on its orbitals (paramagnetism), and a change in orbital velocities and thereby a change in the magnetic momenta of the orbits (diamagnetism).
When the atom has all paired electrons...
O2 has two unpaired electrons, therefore it's quite strong paramagnetism.
But what about (O2)-, the negatively charged O2 ion?
Am I right in assuming that due to the additional electron one unpaired electron will get together with it, so that overall it should still be paramagnetic, but...
Homework Statement
I've been asked to describe the difference between these two, but I'm a but confused.
In my book, it says that paramagnetism is weaker than ferromagnetism, but I don't see why.
If I'm not mistaken, both paramagnetism and ferromagnetism arise from the fact that you...
Homework Statement
I was given a Hamiltonian H = -\muB\sumcos\alpha_{i}
where the sum is over i from i = 1 to i = N
I need the partition function given this Hamiltonian.
Homework Equations
The Attempt at a Solution
I tried using the classical approach where Z_{N} =...
Energy of system of magnetic dipoles is
##E_H=-\mu_0 \vec{\mu}\cdot \vec{H}=-\mu_0\mu_zH##
why sign ''-''?
and ##\mu_z=-g_J\mu_Bm##
Again why ''-'' sign ?
##z## is choosen to be quantization direction, and along that direction is applied field ##H##.
Hi
From what I understand ferromagnetic materials have domains that contain magnetic dipoles that are almost all parallel to each other. However these domains have random directions.
Under a magnetic field the domains in the ferromagnetic material that are magnetized in the field direction...
I know that the different magnetic properties arise from the spin of the electron, I also did some determinations whether a molecule is paramagnetic or diamagnetic (using MO theory), but I don't know how to make a difference between ferromagnetism and paramagnetism. Could someone explain it? And...
As far as I am aware, Pauli Paramagnetism applies to electrons in bands while Curie Paramagnetism applies to localised electrons. Pauli Paramagnetism is usually much weaker because only the electrons near the Fermi Surface can change its spin to align with the magnetic field. On the other hand...
I'm currently in an introductory thermal physics course, and today we
learned about the Boltzmann factor and how to use it to calculate
various quantities with the corresponding probability distribution. All was going well until we got to the subject of paramagnetism.
We supposed a system of...
Homework Statement
A paramagnetic crystal of N ions of spin 1/2, at constant temperature T, is subjected to a magnetic field B. Using the fact that the Helmholtz Free Energy is minimized show that the mean magnetic moment M is:
\mu tanh\frac{\mu B}{kT} Homework Equations
Magnetic...
Hey everyone,
I've noticed that when paramagnetism is derived in the context of stat mech, we only consider the energy levels of the perturbation. Essentially, we take the fine structure of hydrogen, and we perturb it with a B-field, causing the weak zeeman effect to split the energy levels...
Hi,
I am struggling to see the difference in the origins of diamagnetism and paramagnetism.
My understanding of things is that the electrons orbitting an atom constitute a tiny circular current loop, which corresponds to a magnetic dipole moment pointing normal to the plane of that loop...
Hello,
I was wondering if anyone could recommend some really good sources which discuss Paramagnetism and Superparamagnetism in a fairly rigorous manner.
I have been using Kittel, 7th Edition of Intro to Solid State Physics, as a reference source.
I was hoping to find another...
Hi all,
I am looking into the discussions of Pauli paramagnetism (arising from free neutral fermions with spin 1/2) in chapter 11.6 of K. Huang's Stat. Mech. (II ed) and in chapter 31 of Ashcroft and Mermin's Solid State Physics.
It seems to me that these books do not agree on signs.
So...
I need help understanding both of these terms.
I know that diamagnetism is when the valence electrons of the material are paired and repel a magnetic field.
Does that mean it repels like the North side of a magnet to another North side of a magnet?
Or is it they don't attract at all...
[SOLVED] Logs rearranging, relates to paramagnetism
Homework Statement
I want to show that NlnN - n1ln(n1) - n2ln(n2) is equal to:
-N{(n1/N)ln(n1/N) + (n2/N)ln(n2/N)}
apparently i can do this by the artifice of adding and subtracting the term n1lnN and then regrouping.
Homework...
Show that the entropy of a two-state paramagnet, expressed as a function of temperature, is S=Nk[ln(2coshx)-xtanhx], where x=μB/kT. Check that this formula has the expected behavior as T->0 and T->infinity.
Not even sure where to start...
I have a short paper to write this weekend and my physics book doesn't do a very good job of explaining paramagnetism, diamagnetism, and ferromagnetism. Anyone know a good website that gives similarities and differences among those 3 types of magnetism? Thank you.
Simple question, kind of. I know that paramagnetic materials, when in the presence of a magnetic field will have its dipoles orient with the field while diamagnetic materials when introduced to a magnetic field orient opposite to the field. I've read that this has something to do with Lentz's...