Abstract

Structure in 1D conductance below 2e²/h is of particular interest to researchers because new electron interaction effects may be dominant and because theory is incomplete. The 0.7 structure and the related 0.7 analog have been the focus of research. But there is another feature – the 0.5 plateau (at B=0). Although the 0.5 plateau has been reported several times in the past, it never received much attention perhaps because it is somewhat enigmatic. I’ll describe data from an induced GaAs quantum wire which exhibits a clear additional conductance plateau at 0.5*2e²/h in zero magnetic field. The plateau was most pronounced when the potential landscape was tuned to be symmetric using low-temperature scanning-probe techniques. Source-drain energy-spectroscopy and temperature response support the hypothesis that the origin of the plateau is the spontaneous spin-polarization of the transport electrons – a ferromagnetic phase. Such devices may have applications in the field of spintronics, to either generate or detect a spin polarized current without the complications associated with external magnetic fields or magnetic materials.