Intermediate State

intermediate state [‚in·tər′mēd·ē·ət ¦stāt]

(cryogenics)

A state of partial superconductivity that occurs when a magnetic field slightly less than the critical field is applied to a superconducting material below its critical temperature.

(quantum mechanics)

A state through which a system may pass during transition from an initial state to a final state.

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Intermediate State 

a state produced in a superconducting specimen by the action of an external magnetic field or of the magnetic field of a current flowing through the specimen. A superconductor in the intermediate state is a finely divided system of alternating superconducting layers and layers with normal electrical conductivity; the thickness of the layers is about 10^–2cm. In the normal layers the superconductivity is destroyed by the magnetic field there that is close to the critical magnetic field. There is no magnetic field in the superconducting layers. A specimen passes from the superconducting state to the intermediate state when a slowly increasing magnetic field reaches the critical value somewhere in the specimen. The transition from the intermediate state to the normal state occurs when the field reaches the critical value throughout the specimen, and the superconducting layers consequently disappear.

In an intermediate state caused by the action of an external magnetic field, the interfaces between the layers are always at rest. Under the action of a current flowing through the specimen, a dynamic intermediate state can be achieved, in which the interfaces move continuously through the specimen at rates of approximately 10^–2 to 10^–3cm/sec. The interfaces are generated at one of the specimen’s surfaces and disappear at another.

REFERENCES

Shoenberg, D. Sverkhprovodimost’. Moscow, 1955. Chapters 2–4. (Translated from English.)
Andreev, A. F., and lu. V. Sharvin. “Dinamika promezhutochnogo sostoianiia sverkhprovodnikov.” Zhurnal eksperimental’noi i teoreticheskoifiziki, 1967, vol. 53, issue 10, p. 1499.

A. F. ANDREEV