Tagged Questions
7
votes
2answers
173 views
Ferromagnetism with mobile spins
How can electron spins in Iron at room temperature have ferromagnetic order even though they are travelling at very high speeds?
One could argue that spin and motion are completely uncorrelated and ...
-4
votes
3answers
178 views
There must be free positive charges, moving oppositely to electrons for the wire with current to stay neutral
All popular expositions (e.g. these ones) of relativistic electromagnetism claim univocally that electrons in motion become more dense due to the speed. They teach that Lorentz contraction of charges ...
1
vote
1answer
44 views
Understanding drift velocities in currents
I have a doubt about the understanding of drift velocities in a current. My problem is that the textbook speaks very loosely about this. It's like: "well, if we apply a field $E$ then the charges will ...
3
votes
1answer
97 views
Fermi level with Landau levels
So my question is regarding where the Fermi energy is when you have 2D electron gas in an applied magnetic field. My book explains that, using the Landau gauge, you find that the 2D density of states ...
3
votes
3answers
269 views
Why is copper diamagnetic?
Cu has an unpaired electron in 4s, but it is diamagnetic. I thought that it has to be paramagnetic. What am I missing?
2
votes
2answers
354 views
What is the difference between a photon and a phonon?
More specifically, how does a wave-particle duality differ from a quasiparticle/collective excitation?
What makes a photon a gauge boson and a phonon a Nambu–Goldstone boson?
4
votes
0answers
41 views
Order of magnetic phase transitions
Is there any phase transition occur in paramagnetism to diamagnetism transitions state. What should be the order and how will I calculate the order?
6
votes
1answer
925 views
Why are some materials diamagnetic, others paramagnetic, and others ferromagnetic?
Why are some materials diamagnetic, others paramagnetic, and others ferromagnetic?
Or, put another way, which of their atomic properties determines which of the three forms of magnetism (if at all) ...
0
votes
0answers
33 views
Can one obtain saturation magnetization from FMR measurements?
Especially for magnetic thin films. Normally this is done by magneto-optical Kerr effect or SQUID measurements. Or is there a way to calculate the saturation magnetization based on other measured ...
0
votes
1answer
269 views
Pull up and Pull down register
Currently I am working with Pull up and pull down registers and trying to understand what does it mean?
But could not able to understand. I searched in Wikipedia ...
3
votes
1answer
170 views
What is the time correlation function in the Green-Kubo formulation of ionic current?
I am reading a paper, and I came across the Green-Kubo formulation, where the conductivity $\sigma$ of charged particles is related to the time correlation function of the $z$-component of the ...
2
votes
2answers
90 views
What are the specific electronic properties that make an atom ferromagnetic versus simply paramagnetic?
As I understand it, paramagnetism is similar in its short-term effect to ferromagnetism (spins of the electrons line up with the magnetic field, etc.), though apparently the effect is weaker. What is ...
3
votes
1answer
240 views
Lorentz invariance of a frequency- and wavelength- dependent dielectric tensor
Suppose we have a material described by a dielectric tensor $\bar{\epsilon}$. In frequency domain, this tensor depends on the wave frequency $\omega$ and the wave vector $\vec{k}$.
Clearly not all ...
12
votes
3answers
562 views
Shine a light into a superconductor
A type-I superconductor can expel almost all magnetic flux (below some critical value $H_c$) from its interior when superconducting. Light as we know is an electromagnetic wave. So what would happen ...
