title: Influence of surface scattering on the  anomalous conductance plateaus in an  asymmetrically biased InAs/In(0.52)Al(0.48)As  quantum point contact.
abstract: We study of the appearance and evolution of several anomalous (i.e., G < G(0) D 2e(2)/h) conductance plateaus in an In(0.52)Al(0.48)As/InAs quantum point contact (QPC). This work was performed at T = 4:2 K as a function of the offset bias ΔV(G) between the two in-plane gates of the QPC. The number and location of the anomalous conductance plateaus strongly depend on the polarity of the offset bias. The anomalous plateaus appear only over an intermediate range of offset bias of several volts. They are quite robust, being observed over a maximum range of nearly 1 V for the common sweep voltage applied to the two gates. These results are interpreted as evidence for the sensitivity of the QPC spin polarization to defects (surface roughness and impurity (dangling bond) scattering) generated during the etching process that forms the QPC side walls. This assertion is supported by non-equilibrium Green function simulations of the conductance of a single QPC in the presence of dangling bonds on its walls. Our simulations show that a spin conductance polarization as high as 98% can be achieved despite the presence of dangling bonds. The maximum in is not necessarily reached where the conductance of the channel is equal to 0:5G(0).
authors.affiliation: School of Electronics and Computing Systems, University of Cincinnati, Cincinnati, OH 45221, USA.
authors.forename: Partha P
authors.initials: PP
authors.lastname: Das
authors.forename: Nikhil K
authors.initials: NK
authors.lastname: Bhandari
authors.forename: Junjun
authors.initials: J
authors.lastname: Wan
authors.forename: James
authors.initials: J
authors.lastname: Charles
authors.forename: Marc
authors.initials: M
authors.lastname: Cahay
authors.forename: Krishna B
authors.initials: KB
authors.lastname: Chetry
authors.forename: Richard S
authors.initials: RS
authors.lastname: Newrock
authors.forename: Steven T
authors.initials: ST
authors.lastname: Herbert
mesh_terms: D001152:Arsenicals / Q000737:chemistry*; D003198:Computer Simulation; D004553:Electric Conductivity; D004574:Electromagnetic Fields; D007204:Indium / Q000737:chemistry*; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D011789:Quantum Theory; D012542:Scattering, Radiation
chemical_list: D001152:Arsenicals; D007204:Indium; C076773:indium arsenide