How can type-I superconductors have a critical field value?

In summary: When the field is above the critical field, Type I becomes normal and will have the field penetrating through the material! This is the same as Type II above the upper critical field. so I have no idea where you get the idea that it "... can at the same time both be penetrated and not by a magnetic field..."
  • #1
2sin54
109
1
Hello. I am reading about Flux pinning and I have read that only type-II superconductors can be used for that because there is no magnetic field in type-I superconductors (or rather they cannot be penetrated).
If so, how can type-I superconducotrs still have a critical magnetic field strength value in teslas? It seems to me they should be able to withstand any kind of a field due to their property.
 
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  • #2
Gytax said:
Hello. I am reading about Flux pinning and I have read that only type-II superconductors can be used for that because there is no magnetic field in type-I superconductors (or rather they cannot be penetrated).
If so, how can type-I superconducotrs still have a critical magnetic field strength value in teslas? It seems to me they should be able to withstand any kind of a field due to their property.

Why?

To me, it is MORE unusual to have a Type Ii superconductor in which the two states are coexisting together.

If you can accept the upper critical field that exist for Type II, then the same physics apply to the critical field of Type I.

Zz.
 
  • #3
I am sorry but I still do not understand how a type-I superconductor can at the same time both be penetrated and not by a magnetic field. Wikipedia says T-I SC cannot have magnetic field inside of them but that would mean there is no point in talking about critical field value (the value in teslas at which due to the strength of the magnetic field inside the SC the material loses some of its properties).
 
  • #4
Gytax said:
I am sorry but I still do not understand how a type-I superconductor can at the same time both be penetrated and not by a magnetic field. Wikipedia says T-I SC cannot have magnetic field inside of them but that would mean there is no point in talking about critical field value (the value in teslas at which due to the strength of the magnetic field inside the SC the material loses some of its properties).

Er... when the field is above the critical field, Type I becomes normal and will have the field penetrating through the material! This is the same as Type II above the upper critical field. so I have no idea where you get the idea that it "... can at the same time both be penetrated and not by a magnetic field..."

It cannot have a magnetic field inside of it in the superconducting state and while it is belong the critical field. Same as below Hc1 for Type II. It just doesn't have that phase between Hc1 and Hc2 as in Type II. Above Hc for Type I is the same as above Hc2 for Type II!

Zz.
 
  • #5


I can explain that the critical field value in type-I superconductors is related to their ability to maintain a superconducting state. While it is true that type-I superconductors cannot be penetrated by a magnetic field, they still have a critical field value because they can only maintain their superconducting state up to a certain magnetic field strength. Beyond this critical field value, the superconductivity is destroyed and the material becomes resistive.

This critical field value is determined by the material's superconducting properties, such as its critical temperature and critical current density. These properties are affected by factors such as impurities, defects, and temperature. As the magnetic field strength increases, it can disrupt the superconducting state of the material and cause it to become resistive.

In contrast, type-II superconductors have a more complex structure that allows them to withstand higher magnetic fields without losing their superconducting properties. This makes them more suitable for applications such as flux pinning.

In summary, while type-I superconductors may not be able to be penetrated by a magnetic field, they still have a critical field value that is related to their ability to maintain a superconducting state. This value is determined by the material's superconducting properties and can be affected by various factors.
 

1. What is the critical field value of a type-I superconductor?

The critical field value, also known as the upper critical field, is the maximum magnetic field that a type-I superconductor can withstand while maintaining its superconducting state. It is denoted as Hc or Hc1.

2. How does the critical field value of a type-I superconductor compare to that of a type-II superconductor?

The critical field value of a type-I superconductor is lower than that of a type-II superconductor. This is because type-I superconductors have a single critical field where they transition from superconducting to normal state, while type-II superconductors have two critical fields, known as Hc1 and Hc2, with a region of mixed superconducting and normal state in between.

3. What factors affect the critical field value of a type-I superconductor?

The critical field value of a type-I superconductor is affected by the temperature, the purity of the material, and the strength of the magnetic field applied. Higher temperatures and impurities can decrease the critical field value, while a stronger applied magnetic field can increase it.

4. Why is the critical field value important in superconductors?

The critical field value is an important parameter in superconductors because it determines the maximum magnetic field that a superconductor can tolerate before it loses its superconducting state. It also helps in understanding the properties and limitations of different types of superconductors and in designing applications that require high magnetic fields.

5. How can the critical field value be increased in type-I superconductors?

The critical field value of a type-I superconductor can be increased by decreasing the temperature, increasing the purity of the material, and using materials with higher critical field values. Additionally, applying a magnetic field in the direction of the superconducting current can also increase the critical field value, a phenomenon known as the Bean-Livingston barrier.

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