Barnett effect
The Barnett effect was discovered in 1914 by Samuel Jackson Barnett (1873–1956): when a ferromagnet rotates, it behaves as if it were in a magnetic field and is thereby magnetized . A speed of 100 Hz corresponds to a magnetic field of less than 10 −8 Tesla .
The reverse of this effect is the Einstein-de-Haas effect .
With these two effects, the gyromagnetic ratio can be determined with an accuracy of 2 percent.
In 2019 there was also evidence of a Barnett effect in water. In contrast to the classic electronic Barnett effect, the protons of the hydrogen were aligned here ( nuclear Barnett effect ). With NMR , a one percent increase in magnetization compared to the small magnetization induced by NMR was shown at 4000 revolutions per second. At 13,500 revolutions per second, the increase was three percent.
literature
- SJ Barnett: Magnetization by Rotation . In: Phys. Rev. 6, 1915, 239-270.
- SJ Barnett: Gyromagnetic and Electron-Inertia Effects . In Rev. Mod. Phys. 7. 1935, 129-166.
Individual evidence
- ↑ Tycho Sleater, Mohsen Arabgol, Observation of the nuclear Barnett effect, Phys. Rev. Lett., Vol. 122, 2019, p. 177202, abstract . Also: Synopsis: Fast Rotation Polarizes Water , APS May 2, 2019