|
August 11
|
 |
Aug. 11 - 9p
|
 |
||
|
14:30 - 15:00
|
15:00-15:30
|
15:30 - 16:00
|
| Ferromagnetism and Quantum Statistics |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
Masaki Oshikawa |
| Although ferromagnetism has been known to mankind for a long time, its mechanism is rather nontrivial. Ferromagnetism occurs because the electron spins are aligned in the same direction spontaneously, but there is no such explicit fundamental interaction. Rather, it must be caused primarily by quantum effect and spin-independent Coulomb interaction. However, Fermi statistics of electrons is an obstacle to realize ferromagnetism. In fact, Eisenberg and Lieb proved that a wide range of "spin-1/2 boson" models with repulsive interaction has a completely spin-polarized groundstate.
In this talk, I discuss a possible mechanism of ferromagnetism in spin-1/2 fermions. We consider a U= infinity Hubbard model with a magnetic flux, which only couples to the orbital motion and not to the spin. When the flux per plaquette matches the density of fermions, the fermion may be transmutated into boson and the ferromagnetism could be realized. We study the model numerically and find an evidence that the ferromagnetism is indeed realized by the statistical transmutation. [1] Y. Saiga and M. O., Phys. Rev. Lett. 96, 036406 (2006). |