London penetration depth
E48480
The London penetration depth is a characteristic length scale in superconductors that measures how far an external magnetic field can penetrate into the material before being exponentially screened.
Statements (49)
| Predicate | Object |
|---|---|
| instanceOf |
characteristic length scale
→
physical quantity → superconductivity concept → |
| appearsIn | Ginzburg–Landau theory of superconductivity → |
| appliesTo | superconductor → |
| assumes | local electrodynamics in London theory → |
| canBeMeasuredBy |
magnetization measurements
→
microwave resonator techniques → muon spin rotation → optical reflectivity → tunnel diode resonator method → |
| characterizes | exponential decay of magnetic field → |
| definedAs | distance over which magnetic field decays by factor e in a superconductor → |
| dependsOn |
charge of Cooper pairs
→
effective mass of Cooper pairs → superfluid density → |
| describes | magnetic field penetration in superconductors → |
| divergesAt | critical temperature → |
| entersExpression | screening current density in superconductors → |
| fieldOfStudy |
condensed matter physics
→
low-temperature physics → |
| hasAlternativeSymbol | λ_L → |
| hasDimension | length → |
| hasSymbol | λ → |
| increasesWith | temperature → |
| isLargerFor | dirty or disordered superconductors → |
| isShorterThan | skin depth in normal metals at low frequencies → |
| isSmallerFor | materials with higher superfluid density → |
| measuredIn |
angstrom
→
meter → nanometer → |
| namedAfter |
Fritz London
→
Heinz London → |
| occursInEquation | B(x) = B(0) exp(-x / λ) → |
| partOfTheory | London equations → |
| relatedByFormula | λ^2 = m / (μ0 n_s q^2) in London theory → |
| relatedTo |
Meissner effect
→
coherence length → magnetic susceptibility of superconductors → superconducting energy gap via temperature dependence → |
| symbolUses |
m for effective mass in its formula
→
n_s for superfluid carrier density in its formula → q for carrier charge in its formula → μ0 for vacuum permeability in its formula → |
| temperatureDependent | true → |
| typicalMagnitude |
hundreds of nanometers for high-temperature superconductors
→
tens of nanometers for conventional superconductors → |
| usedIn | classification of type I and type II superconductors → |
| usedToDefine |
Ginzburg–Landau theory of superconductivity
→
surface form:
Ginzburg–Landau parameter
|
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.