Superconductivity and carbon nanotubes, are Type I, while almost all impure and compound superconductors are Type II. Conversely, a spinning superconductor generates a magnetic field, precisely aligned with the spin axis. The effect, the London moment, was put to good use in Gravity Probe B. This experiment measured the magnetic fields of four superconducting gyroscopes to determine their spin axes. This was critical to the experiment since it is one of the few ways to accurately determine the spin axis of an otherwise featureless sphere. Superconductivity was discovered on April 8, 1911 by Heike Kamerlingh Onnes, who was studying the resistance
Friedrich Hasenöhrl Friedrich Hasenöhrl Friedrich Hasenöhrl (; 30 November 1874 – 7 October 1915), was an Austrian physicist. Friedrich Hasenöhrl was born in Vienna, Austria-Hungary in 1874. His father was a lawyer and his mother belonged to a prominent aristocratic family. After his elementary education, he studied natural science and mathematics at the University of Vienna under Joseph Stefan (1835–1893) and Ludwig Boltzmann (1844–1906). In 1896, he attained a doctorate under Franz-Serafin Exner with a thesis titled "Über den Temperaturkoeffizienten der Dielektrizitätskonstante in Flüssigkeiten und die Mosotti-Clausius'sche Formel". He worked under Heike Kamerlingh Onnes in Leiden at the low temperature laboratory, and