Korringa-Like Nuclear Spin-Lattice Relaxation in a 2DES at $\nu = 1/2$

Via a resistively-detected NMR technique, the nuclear spin lattice relaxation time $T_{1}$ of $^{71}$Ga at low temperatures has been measured in a GaAs/AlGaAs heterostructure containing two weakly-coupled 2D electron systems (2DES), each at Landau level filling $\nu = 1/2$. Incomplete electronic spin polarization, which has been reported previously [1,2] for low density 2DESs at $\nu = 1/2$, should facilitate hyperfine- coupled nuclear spin relaxation owing to the presence of both electron spin states at the Fermi level. Within composite fermion theory, a Korringa law temperature dependence: $T_{1}T = constant$, is expected for temperatures $T<1$ K. Our measurements made at temperatures in the range 35 mK $