Strains in heterostructures detected by standard NMR

Using standard nuclear magnetic resonance (NMR) technique, we have succeeded in observing the strains in an Al0.3Ga0.7As/GaAs heterostructrued sample through Al nuclear spins. From the observed quadrupolar-split frequency, the electric field gradient is found to be roughly 50 times as large as those observed through 69Ga nuclear spins in resistivity-detected NMR.