What is Superconductivity: Definition and 140 Discussions
Superconductivity is a set of physical properties observed in certain materials where electrical resistance vanishes and magnetic flux fields are expelled from the material. Any material exhibiting these properties is a superconductor. Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered even down to near absolute zero, a superconductor has a characteristic critical temperature below which the resistance drops abruptly to zero. An electric current through a loop of superconducting wire can persist indefinitely with no power source.The superconductivity phenomenon was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes. Like ferromagnetism and atomic spectral lines, superconductivity is a phenomenon which can only be explained by quantum mechanics. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor during its transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.
In 1986, it was discovered that some cuprate-perovskite ceramic materials have a critical temperature above 90 K (−183 °C). Such a high transition temperature is theoretically impossible for a conventional superconductor, leading the materials to be termed high-temperature superconductors. The cheaply available coolant liquid nitrogen boils at 77 K, and thus the existence of superconductivity at higher temperatures than this facilitates many experiments and applications that are less practical at lower temperatures.
Hi!
In reading about Superconductivity and its current state of only being achieved in super cooled or heated materials. This sparked a question the following question:
What is the result of the trade off between energy saved by avoiding dissipation through the natural resistance of a material...
In Feymann's seminar on superconductivity, there was this equation (21.28) ##\oint_C \nabla \theta\cdot dl = \frac q \hbar \Phi##. But the gradient theorem demands that ##\oint_C \nabla \theta\cdot dl=0##
This question is more complicated than it seems, most physicists cannot answer it unambiguously and there is no experiments to the issue. Imagine, a persistent supercurrent flows in a SC aluminum ring. Then we connect the SC aluminum ring (without solder) to an aluminum wire, the second end of...
So this might be long question that requires some literature review but I will try condense it as much as possible such that hopefully I can get some help without the reader having to review the related paper.
So I will start off by saying that I am involved in a honours thesis in which I need...
I was wondering if anyone knows of any technical pop-sci books about condensed matter physics and/or superconductivity that are at the technical level of something like the "A Very Short Introduction" series or the Feynman lectures. That is, something that goes sufficiently into depth into the...
Wikipedia says that superconductivity is a phenomenon which can only be explained by quantum mechanics. Maybe there is a close relation between the connection of superconductor parts and quantum entanglement? If yes, a question arises: what is the speed of electric current flowing through the...
An interesting paper in NATURE "A superconductor free of quasiparticles for seconds"
https://www.nature.com/articles/s41567-021-01433-7
showing that superconducting (paired) electrons don't hop into normal states for seconds. The measurement device detects single pair-breaking-events for a large...
In the BCS theory the Cooper pair density depends on temperature, meaning that pairs can be created/annihilated by temperature variations. Obviously, momenta of annihilated pairs dissipate on the atom lattice, so an initial supercurrent dissipates. On the other hand, in some experiments a...
I am on my first year of my master's degree in nuclear and particle physics, and right now i am ending my first semester, where i decided to take a course in physics of semiconductors. As i end this semester i start to wonder if there was any use in learning about this subject, as it seems like...
We have a one dimensional lattice with a lattice constant equal to a (I'm omitting vector notation because we are in 1D). The reciprocal lattice vector is k_n=n\frac{2 \pi}{a}.
So to get the nearest neighbour approximation I need to sum over k = -\frac{2 \pi}{a}, 0, \frac{2 \pi}{a}.
If I...
This question is for those familiar with the BCS theory of superconductivity or familiar with R.D. Mattuck's book “A Guide to Feynman Diagrams in the Many-Body Problem.” I am working my way through the book, and I am stumped by some of the problems at the end of chapter 15 (superconductivity)...
Hello,
I have a question about the Higgs mode in superconductivity. In this doc, it is said, page 12, that the Higgs mode has no electric charge. But it couples nonlinearly with the photon (in the Ginzburg-Landau theory there is a term A²h with A the vector potential and h the Higgs mode). So...
Hello! Recently, I became interested in superconductors. And I talked to professor in my uni. Here's my question, since superconductors have zero resistance by definition, so, in stable condition (after passing transient phase) the current should be infinite. Which implies that according to...
I am doing a project where the final scope is to find an extra operator to include in the proca lagrangian. When finding the new version of this lagrangian i'll be able to use the Euler-Lagrange equation to find the laws of motion for a photon accounting for that particular extra operator. I...
One of the first starting points of introducing BCS theory in a superconductor is applying a theorem stating that the ground-state of a quantum system has an expectation value for its momentum of zero. You then use this to say that an electron must pair with another electron of equal and...
For high temperature superconductivity, people usually say two quasifree electrons are pairing, one is spin up and the other one is spin down.
So, if that is the case, each two electrons will have zero spin angular momentum. Since the superconductivity is the magnetic properties and spin is the...
Why when a certain current limit is breached is superconductivity destroyed in a material, what atomically causes this effect when J > Jc? Secondary question what causes H0's value to be higher or lower atomically and chemically for a given material?
Hello,
I am interested in physics of cuprate high temperature superconductors (Cuprate_SC)
However, I heard that it is "out-of-dated" topic in solid state physics and almost impossible to find group/foundation to do research in this field.
I am doing PhD right now and I consider moving...
So far the best I've been able to come up with is to use ##\vec{B} = \mu_0 \vec{H}## which gives me
i_c = H 2\pi r
j_c = \frac{H 2\pi r}{\pi r^2} = \frac{2H}{r}
\therefore B = \mu_0 \frac{r j_c}{2}
I'm fairly confident this is just terrible math and physics on my behalf but I'm struggling to...
On 23rd July, 2018, physicists from Indian Institute of Science (IISc) Bangalore, said that they had discovered superconductivity at room temperature. The paper in arxiv aroused doubts in the scientific world, but nothing was said after that.
However, the team has reviewed the paper to a new...
I am wondering what is the physical evidence that Cooper pairs are indeed the ones responsible for superconductivity. These pairs consist of two electrons with opposite momentum, forming a boson with null momentum.
But what about pairs that would consist of, say, 6 electrons (or even more)? Of...
It is often said that the mechanical properties of metals are mostly due to their free electrons. I'm talking about malleability, ductility and hardness.
So, when they suffer a superconductive transition, I expect a drastic change in their mechanical properties, but I haven't found anything on...
As shown in the figure, the aircraft includes a geomagnetic field convergence layer, which is a superconductor material. The geomagnetic field convergence layer repels the direction of changing the geomagnetic field, so that the geomagnetic field passes between the upper and lower converging...
From what I'm reading about superconductivity, Cooper pairs, which are responsible for superconductivity (SC) arise from the interaction between electrons and phonons. Also, from what I've read, it is generally said that SC occurs below a certain critical temperature T_c (let's stick to type I...
What I mean by that - is it possible to model a system and somehow obtain them as a result? (in FEMM 4.2 or Comsol for example)
Or is their forming still not yet explored enough?
I don’t seem to see discussion of this result on PF, so I invite such:
https://arxiv.org/abs/1704.07685
This suggests the possibility no new theory beyond BCS is necessary.
I’m interested especially in comments by members who work in this or related fields.
Hello,
Is Superconductivity an example of emergence where you can't predict it's occurence by just working with the Schroedinger Equation?
If Superconductivity is an emergence, what do you call those none emergence processes?
Perhaps some examples would enlighten. Thanks to all those who can...
As is well known, superconductivity is described as a property of zero-resistance for electrical current, however, I want to know, is there any material with superconductivity for light beams, in which the light beams can propagate with no losses?
Second London Equation, which is supposed to represent the current in a superconductor. (SI units)
∇×j=-(ns e2/m) B.
Lets have a look at a super-conducting wire. The magnetic field is:
B=μ0Ir/(2πr)
Where Ir is the current enclosed by the radius r.
We are talking about the current at some depth...
Hey all! Thanks for reading. I'm currently following along in some reading and had some trouble with re-writing a Hamiltonian in Bogluibov-de Gennes form using Nambu notation (Nambu spinors). Here is the low down:
Say we have a Hamiltonian:
\frac{1}{2} \sum_{i=1}^{N} c_{i}^{\dagger} D c_{i} +...
Hello! So I'm really stuck in a personal quest to derive Kitaev's 1D p wave superconductivity model, and I'm stuck on the seemingly simplest part.
1. Homework Statement
In the Bogluibov transformation, we get two coefficients from the equations |v_{k}|^{2}+ |u_{k}|^{2}= 1...
Hi folks,
It is an elementary question for people expert in superconductivity.
I know there is a theory, the BCS theory, and the GIzburg Landau theory too that apparently explains superconductivity.
My question is, if I give you a unit cell would you be able to tell me the temperature at...
Hi,
I am new to superconductivity and have been doing a lot of reading to try and become familiar with it. I have come across a few questions that I would be grateful is someone could answer. I am confused about the mechanism that describes the expulsion of magnetic fields from inside a...
When a supercooled type two superconductor is subjected to a static magnetic field, the superconductor pins to the flux of the field (the mixed-state meissner effect is apparent).
What happens if it is subjected to a continuously changing magnetic field, assuming the superconductivity takes...
I am currently doing a experimental project work on superconductors. I am supposed to study properties of FeTeSe.
I am having trouble understanding the difference between Zero-Field Cooling and Field Cooling. In both cases, I am measuring magnetization with varying temperature (from lower to...
Hi All,
I was wondering how I would go about creating a circular maglev track using electromagnets? The idea is to have more control over it and to eventually write a piece of code that would allow changes in the strength of the magnetic field potentially? I was just wondering how it would work...
How large would a superconducting magnetic energy storage device be if it were to safely carry 100 kilowatt-hours of energy? How much cryogen (liquid nitrogen) would it consume per hour if the device were made from high-temperature superconducting materials (YBCO or similar).
Hello,
This problem is about cooper pair formation and what happens with the calculations if there is an attractive potential between electrons but it is not in the presence of a filled fermi surface.
1. Homework Statement
Two electrons just above the filled Fermi Surface of a material can...
What does underdoped cuprates mean?
As I guess cuprate is underdoped when hole concentration is less then optimal doping.
Is it correct?...:rolleyes:
Thank you very much in forward
Good day! i really need your help, I want to know the effect of Dopant (for Example Manganese) in BSCCO (for example Bi-2212) on it's Resistivity? i read some articles saying it increases the critical temperature of the superconductor, But it didn't explain why, and how is that related to the...
I read in a book "Optoelectronic Integration: Physics, Technology and Applications" edited by Osamu Wada.
Ballistic Conduction and Superconductivity are both electron transport that are not affected by the collisions and scatterings.
Ballistic conduction or Ballistic transport occurs when the...
Ballistic conduction occurs when the length of the conductor is smaller than the mean free path of the electron.
Ballistic conduction differs from superconductivity due to the absence of the Meissner effect in the material. A ballistic conductor would stop conducting if the driving force is...
Hello guys, I will be starting my M.S Program in Solid State Electronics and was also curious about looking into quantum computing/superconductors. So can you guys suggest introductory levels books on quantum computing and and superconductors?
I have an okay background in Physics (just...
There is a conservation law for superconductors " the flux through a superconducting ring cannot change". This can be shown using Faraday's law: -
E.M.F=-d/dt (BA) where B is the measured magnetic field passing through the ring and A is the area enclosed by the ring
therefore for a ring...
Curious: say, it takes a particular piece of superconductive material "x" seconds to reach the state when submerged in liquid nitrogen. Now, say we try to do the same in presence of a (strong) magnetic field. Does x increase, decrease or does it stay the same?
My money is on increasing, because...