Questions tagged [superconductivity]
Superconductivity is the transmission of current with no resistive losses, and is one of the most active areas of condensed matter physics research.
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What is a $p_x + i p_y$ superconductor? Relation to topological superconductors
I often read about s-wave and p-wave superconductors. In particular a $p_x + i p_y$
superconductor - often mentioned in combination with topological superconductors.
I understand that the overall ...
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Why is high temperature superconductivity so hard to solve?
The phenomenon of high temperature superconductivity has been known for decades, particularly layered cuprate superconductors. We know the precise lattice structure of the materials. We know the band ...
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Should a superconductor act as a perfect mirror?
I have been told that metals are good reflectors because they are good conductors. Since an electric field in conductors cause the electrons to move until they cancel out the field, there really can'...
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How can Ohm's law be correct if superconductors have 0 resistivity?
Ohm's law states that the relationship between current ( I ) voltage ( V ) and resistance ( R ) is
$$I = \frac{V}{R}$$
However superconductors cause the resistance of a material to go to zero, and ...
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Why don't superconductors, which have zero electrical resistance, violate the second law of thermodynamics?
There are bunch of questions on here asking whether superconductors really have exactly zero resistance and answers saying they do. My question is how this doesn't violate the second law of ...
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Are room temperature superconductors theoretically possible, and through what mechanism?
At the moment, the highest critical temperature superconductor known to science (or myself, at least) is mercury barium calcium copper oxide. With a $T_{c}$ of roughly 133 K, that's well above the ...
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Do topological superconductors exhibit symmetry-enriched topological order?
Gapped Hamiltonians with a ground-state having long-range entanglement (LRE), are said to have topological order (TO), while if the ground state is short-range entangled (SRE) they are in the trivial ...
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Why is there a band structure for strongly correlated systems?
The existence of band structure of a crystalline solid comes from the Bloch theorem, which relies on the independent-electron approximation. Why do people still talk about the band structure for a ...
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Is an electron a superconductor?
A superconductor has zero resistance. What about an electron in a vacuum? Could this simple system be considered superconducting?
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Mean field equations in the BCS theory of superconductivity
In BCS theory, one takes the model Hamiltonian
$$
\sum_{k\sigma} (E_k-\mu)c_{k\sigma}^\dagger c_{k\sigma} +\sum_{kk'}V_{kk'}c_{k\uparrow}^\dagger c_{-k\downarrow}^\dagger c_{-k'\downarrow} c_{k'\...
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What makes a superconductor topological?
I have read a fair bit about topological insulators and proximity induced Majorana bound states when placing a superconductor in proximity to a topological insulator.
I've also read a bit about ...
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What is the link between the BCS ground state and superconductivity?
The link between the BCS ground state
$$
\left|\Psi_\mathrm{BCS}\right\rangle = \prod_k \left( u_k - v_ke^{i \phi} c_{k\uparrow}^{\dagger} c_{-k\downarrow}^{\dagger}\right) \left|0\right\rangle
$$
and ...
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What observables are indicative of BCS Cooper pair condensation?
What observables are indicative of BCS Cooper pair condensation?
"Thought" experiments and "numerical" experiments are allowed.
This question is motivated by the question Has BCS Cooper pair ...
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Can a superconducting wire conduct unlimited current?
A superconducting wire has no electrical resistance and as such it does not heat up when current passes through it. Non-superconducting wires can be damaged by too much current, because they get too ...
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Superconductor symmetry breaking
When water freezes continuous translational symmetry is broken. When a metal becomes superconducting, what is the symmetry that gets broken?
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Intuitive reasons for superconductivity
Superconductivity
I read in a book "Physics - Resnik and Halliday" the explanation of Type-I Superconductors {cold ones} that:
The Electrons that make up current at super-cool temperatures ...
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Is current in superconductors infinite? If they have 0 resistance then I (V/R) should be infinite? [duplicate]
I learned many years ago that according to Ohm's law, current is equal to voltage divided by resistance. Now if superconductors have zero resistance then the current should be infinite.
Moreover the ...
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How can I put a permanent current into a superconducting loop?
I know that you can use induction to create a current in a superconducting loop, but this only works as long as the coil that induces the field has a current flowing through it. And obviously, this ...
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How can you measure the zero resistance in a superconductor?
As we know, superconductors have zero resistance. How can we measure the zero resistance in a superconductor?
Can you devise an experiment to measure the zero value of resistance?
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Optical equivalent of a superconductor
Is there some material state that can propagate light indefinitely without dissipation or absorption, like superconductors are able to transmit current indefinitely?
If not, then the question is, why ...
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What is the difference of the gap between superconductor and insulator?
This is what I learned from textbook. An insulator is insulate as the gap between the valence band and the conduction band and the fermi level lies in the gap. A superconductor is super electronically ...
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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 ...
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Usage of helium in MRIs
More and more articles pop up on the shortage of helium, and on the importance of it. Its usage in MRI's spring to mind for example. I looked it up and found out that helium is used for its 'low ...
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Why does a superconductor obey particle-hole symmetry?
We normally solve the Bogoliubov-de Gennes (BdG) equations in order to compute the energy spectrum of a superconductor. The Nambu spinor is a common object that is used in formulating these equations. ...
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What is the Difference Between BCS Theory and Ginzburg-Landau Theory?
What is the Difference Between BCS Theory and Ginzburg-Landau Theory?
I have been studying Superconductivity and I know that Both of the theories (BCS Theory and Ginzburg-Landau Theory) can be used ...
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Validity of mean-field approximation
In mean-field approximation we replace the interaction term of the Hamiltonian by a term, which is quadratic in creation and annihilation operators. For example, in the case of the BCS theory, where
$...
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The nature of the BCS ground state
My question concerns which electrons in a superconductor form Cooper pairs in the BCS ground state, i.e., all of them or only part of them. I am currently reading about superconductivity from Chap. 10,...
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Can superconducting magnets fly (or repel the earth's core)?
If a superconducting magnet and appropriate power supply had just enough $I\cdot s$ (current $\cdot$ length) so that when it was perpendicular to the earth's magnetic field, the force of the ...
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Why are superfluid vortex lattices stable?
Both (a) neutral superfluids that are externally rotated, and (b) type-II superconductors (i.e. charged superfluids) under applied magnetic fields between the critical fields $h_{c1}$ and $h_{c2}$, ...
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Are there topological non-trivial states in zero dimension?
The periodic table of topological insulators and superconductors suggests that there can be topological non-trivial phases in zero dimension in non-interacting system with certain symmetries.
A 0D ...
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