NMR probing of the spin polarization of the ν=5/2 quantum hall state

Abstract

Resistively detected nuclear magnetic resonance is used to measure the Knight shift of the As75 nuclei and determine the electron spin polarization of the fractional quantum Hall states of the second Landau level. We show that the 5/2 state is fully polarized within experimental error, thus confirming a fundamental assumption of the Moore-Read theory. We measure the electron heating under radio frequency excitation and show that we are able to detect NMR at electron temperatures down to 30 mK. © 2012 American Physical Society.