All-optical magnetic resonance in semiconductors
A scheme is proposed wherein nuclear magnetic resonance (NMR) can be induced and monitored using only optical fields. In analogy to radio-frequency fields used in traditional NMR, circularly polarized light creates electron spins in semiconductors whose hyperfine coupling could tip nuclear moments. Time-resolved Faraday rotation experiments were performed in which the frequency of electron Larmor precession was used as a magnetometer of local magnetic fields experienced by electrons in n-type gallium arsenide. Electron spin excitation by a periodic optical pulse train appears not only to prepare a hyperpolarized nuclear moment but also to destroy it resonantly at magnetic fields proportional to the pulse frequency. This resonant behavior is in many ways supportive of a simple model of optically induced NMR, but a curious discrepancy between one of the observed frequencies and classic NMR values suggests that this phenomenon is more complex.
Kikkawa
JM
Department of Physics, University of California, Santa Barbara, CA 93106, USA.
Awschalom
DD