Kohler's rule

The Kohler rule states that a of the magnetic flux density -dependent resistivity for small magnetic flux densities extrapolated may be: ${\displaystyle B}$ ${\displaystyle \rho }$

${\displaystyle {\frac {\Delta \rho }{\rho _{0}}}=F\cdot {\frac {B}{\rho _{0}}}}$

With

• ${\displaystyle F}$a universal, temperature- independent function that only depends on material and geometry. ${\displaystyle T}$

This rule delivers precise results, especially at flux densities below 30  mT . The following applies to small magnetic flux densities:

${\displaystyle {\frac {\Delta \rho }{\rho _{0}}}\propto B^{2}}$

In particular, the specific resistance of superconducting materials can be measured by applying this rule . To do this, an external supercritical flux density is applied below the critical temperature , so that the superconductor leaves the Meissner phase and the resistance becomes measurable. The specific resistance can then be approximately determined from the measured values ​​using Kohler's rule.

Individual evidence

1. ↑ James C. Garland, R. Bowers: Evidence for Electron-Electron Scattering in the Low-Temperature Resistivity of Simple Metals , Physical Review Letters, Vol. 21, 1968, 1007-1009

Web links

• Magnetic resistance, University of Tübingen, PDF file (102 kB)