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1

In fact hydrogen is an old idea to get a high temperature superconductor, based exactly on the idea of its light mass. The problem is that one has to start from metallic hydrogen, which is a problem on itself. It has not yet been fully experimentally confirmed in the lab. You need pressures of several hundreds of GPa to achieve that (100 GPa is about 1 ...


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Is it true that superconducting electromagnets don't need any power? So... energy to created a magnetic field via a superconductor would be zero? They have to be at very low temperatures, that takes a lot of energy. The ATLAS Barrel Toroid was first cooled down over a six-week period in July-August to reach –269°C . It was then powered up ...


3

The most truthful answer, to my mind, to this is simply "because it often works in practice." It is not obvious, a priori, that band structure should apply to any realistic solid. The Coulomb interaction is typically of the order of the Fermi energy. Nonetheless, thanks to the magic of Fermi liquid theory, this strong interaction somehow only results in ...


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So my question is where I am wrong or more appropriately what wrong steps I have made in my calculation. When you lower mathematically the resistance while fixing the current, this means electric field decreases, but magnetic does not. In the limit $\rho\rightarrow 0$ all the initial energy is in the magnetic field and can be expressed through ...


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The problem is in your assumptions. If you have an E-field in the loop then the potential (voltage) would be increasing as you go around it. If you have a current in the wire, there must be a magnetic flux through the loop. The magnetic field has energy, which you are not accounting for. The magnetic field cannot penetrate a superconductor, so it is ...


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Usually, when talking of the "band structure" of such a system one either refers to the non-interacting band structure (which relates to the free Green functions occuring in many methods to handle the interactions, like perturbation expansions or DMFT), or to the sharp features usually visible in the spectral function (which is more or less experimentally ...


0

To be correct it needs to make falsifiable predictions. Does it predict the critical temperatures of known materials? Does it allow us to determine which kinds of materials would be superconducting at, say, room temperature? We already have some OK theories for low temperature how is this different, it sounds so vague and imprecise. And even if it ...


1

Every phase transition has an order parameter: something that vanishes above the transition temperature and is finite below. In superconductors, the order parameter is a complex quantity related to the superconducting gap: $\Delta = |\Delta| e^{i \phi}$. In BCS theory, there is a self-consistent equation for the gap: $\Delta_k = -\sum_q V_{kq} ...


3

This is a well advanced discussion but I'll give my two cents here. There is a major quantum mechanics difference between a superconductor and electrons in vacuum. Electons in vacuum have each its own wave function. In a superconductor, Cooper pairs condensate into a single wave function. So what? Well, it becomes very easy to scatter electrons in ...


3

In condensed matter "bulk" does not refer to the dimensionality of the problem but the location in the material. It refers to the volume of the crystal, as opposed to, e.g., surface effects. Many organic conductors behave as 1D systems, yet you can talk about bulk properties. Copper oxide superconductors have a 2D physics. However, often you will find ...


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The lower part is not filled with quasi-particles. At zero Kelvin, in zero magnetic field and with zero disorder all free electrons condense and form the superconducting condensate. The semiconductor model now describes the breaking of Cooper pairs not as resulting in two electron-, but in one electron- and hole-like excitation. As you are potentially ...


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My answer will be brief unfortunately. Here's how I think about it. Electrons in the band that is near the Fermi energy interact through some attractive force. The ground state of this system is the superconducting state, with all those electrons paired up and you have a superconducting condensate which is that "Cooper sea" Now we consider low-energy ...



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