Zero Bias Tunneling Resonance at Filling Factor $\nu_T=1$ in GaAs Hole Bilayers

Previous tunneling and transport measurements on bilayer two dimensional carrier systems at total filling factor $\nu_T = 1$ provide strong evidence for an excitonic ground state with small but finite dissipation. We present, for the first time, tunneling conductance measurements of bilayer two dimensional {\it hole} systems in a strongly interacting regime ($1.1 < d/l_B < 1.3$, where $d$ is the interlayer distance and $l_B$ is the magnetic length). We find that the zero bias tunneling resonance at $d/l_B=1.2$ has a larger amplitude and a weaker temperature dependence than existing data from electron samples ($d/l_B=1.5-1.8$) for the range of temperatures where we have taken data ($300mK-600mK$). This work was supported by the DOE and NSF.