What is difference between penetration depth and coherence length?

The London penetration depth refers to the exponentially decaying magnetic field at the interior surface of a superconductor. The fact of exclusion of magnetic fields from the interior of the superconductor is called the Meissner effect. An independent characteristic length is called the coherence length.

What are type 1 and type 2 superconductor?

The difference between type I and type II superconductors can be found in their magnetic behaviour. A type I superconductor keeps out the whole magnetic field until a critical app- lied field Hc reached. A type II superconductor will only keep the whole magnetic field out until a first critical field Hc1 is reached.

What is type 1 superconductor example?

In type-I superconductors, superconductivity is abruptly destroyed via a first order phase transition when the strength of the applied field rises above a critical value Hc. This type of superconductivity is normally exhibited by pure metals, e.g. aluminium, lead, and mercury.

How is London penetration depth calculated?

London penetration depth can be measured by muon spin spectroscopy when the superconductor does not have an intrinsic magnetic constitution. The penetration depth is directly converted from the depolarization rate of muon spin in relation which σ(T) is proportional to λ2(T).

What is the coherence length of Cooper pair in crystalline material?

The average distance between the two electrons in a Cooper pair is known as the coherence length, ξ. Both the coherence length and the binding energy of two electrons in a Cooper pair, 2∆, depend upon the particular superconducting material.

Which type magnetic material is suited for superconductivity?

Type II superconductors have a different magnetic behaviour. Examples of materials of this type are niobium and vanadium (the only type II superconductors among the chemical elements) and some alloys and compounds, including the high-Tc compounds.

How is aluminum a superconductor?

Specifically, they found out that while single atoms of aluminum only turn superconductive at very low temperatures (around 1 K), so-called “superatoms” (clusters of evenly spaced atoms that behave as a single atom) of aluminum turn superconductive at much higher temperatures, around 100 K.

What is penetration depth of a superconductor on what factors does it depend what is the penetration depth for PB?

The characteristic length, λ, associated with the decay of the magnetic field at the surface of a superconductor is known as the penetration depth, and it depends on the number density ns of superconducting electrons.

Which are the high temperature superconductors?

The superconductor with the highest transition temperature at ambient pressure is the cuprate of mercury, barium, and calcium, at around 133 K. There are other superconductors with higher recorded transition temperatures – for example lanthanum superhydride at 250 K, but these only occur at very high pressures.

What are London penetration depth and coherence length in superconductivity?

Arising in the theoretical and experimental investigations of superconductivity are two characteristic lengths, the London penetration depth and the coherence length. The London penetration depth refers to the exponentially decaying magnetic field at the interior surface of a superconductor.

What is the characteristic length of a superconductor?

Characteristic Lengths in Superconductors. Arising in the theoretical and experimental investigations of superconductivity are two characteristic lengths, the London penetration depth and the coherence length. The London penetration depth refers to the exponentially decaying magnetic field at the interior surface of a superconductor.

What is the difference between Type I and Type II superconductors?

Type I superconductors have larger coherence length and shorter magnetic penetration depth, however, type II superconductors have larger magnetic penetration depth and smaller coherence length. Normally, high-temperature superconductors and unconventional superconductors are type II.

How to measure the penetration depth of a superconductor at 0 K?

So, accurate and precise measurements of the absolute value of penetration depth at 0 K are very important to understand the mechanism of high-temperature superconductivity. London penetration depth can be measured by muon spin spectroscopy when the superconductor does not have an intrinsic magnetic constitution.