Influence of gate voltage on nonlocal resistance in GaAs/ AlGaAs heterostructure at high magnetic fields

Abstract

The nonlocal Shubnikov-de Haas (S-dH) resistance has been investigated in a GaAs/AlGaAs wire with Schottky gates across the separation path between current and voltage probes. With decreasing electron concentration below the gate, the up-spin S-dH oscillation peak vanishes at higher electron concentration than the down-spin peak. This can be understood by the fact that the bulk current at the down-spin peak actually consists of both down- and up-spin states and that the one at the up-spin peak consists mostly of the up-spin state. Further the influence of extra probes, which have ostensibly nothing to do with the four-terminal resistance, has been studied by disconnecting the extra probes electrically by the gate across the extra terminal. When the extra probe is disconnected, both normal and nonlocal S-dH oscillation peaks at high magnetic fields are altered.