All-optical NMR probes semiconductors

17 Jun 2002

A nuclear magnetic resonance (NMR) system where the signal is induced and monitored with only optical fields could be used to probe the fine structure of semiconductors and other materials, according to researchers at the University of California, Santa Barbara.

Reporting in the 21 January 2000 issue of the journal Science, JM Kikkawa and DD Awschalom described magnetic resonance close to nuclear frequencies that could be seen in gallium arsenide semiconductors when they are pulsed with a Ti:sapphire laser at about 76 MHz.

In the research, circularly polarized light creates electron spins in semiconductors and these trigger the flipping of nuclear spins, which can be characteristic of the hyperfine structure of the semiconductor.

The optical pumping and detection of NMR are interesting because they offer a sensitive measure of localized electronic states in semiconductors.

SH