London moment

The London moment is the quantum mechanical phenomenon named after the physicist Fritz London , that a superconductor has a magnetic moment that only depends on the type of charge carrier, not on the shape, size and band structure of the body, and when it rotates it generates a magnetic field whose Orientation coincides with the axis of rotation of the superconductor.

The magnetic field strength of the rotating superconductor is

${\displaystyle H=-{\frac {2Mc}{Q}}\ \omega }$

with M and Q for mass and charge of the charge carriers of the superconducting phase, for Cooper pairs that is and . ${\displaystyle M=2m_{e}}$ ${\displaystyle Q=2e}$

One application is the reaction-poor detection of the rotation axis of gyroscopes in weightlessness, see Gravity Probe B .

See also

• Barnett effect

Individual evidence

1. ↑ J. Tate et al .: Determination of the Cooper-pair mass in niobium . In: Physical Review B . 42, No. 13, 1990, p. 7885. bibcode : 1990PhRvB..42.7885T . doi : 10.1103 / PhysRevB.42.7885 .