Tilt-Induced Anisotropic Phases in Wide GaAs Quantum Wells

Abstract

Abstract. Tilt induced anisotropic transport is observed in a series of three wide GaAs quantum wells. In the absence of tilt the transport is isotropic and well developed quantum Hall states are observed. For large values of tilt (>60) the quantum Hall states at =5 and 7 are replaced by strongly anisotropic states in the two widest wells, occurring at slightly lower values of  for the widest well. A similar transition is also seen at =9 in the widest quantum well. This transition is not observed in the narrowest quantum well up to the largest tilt angle measured.

Strong transport anisotropy in Ge/SiGe quantum wells in tilted magnetic fields

“…21 reported a strong anisotropy at ν = 4 of a 2DEG in Si/SiGe in a narrow range of tilt angles, with the hard axis along B . Similar observations were made in wide GaAs/AlGaAs quantum wells with two occupied subbands [22,23]. However, we are not aware of any reports that B can induce significant anisotropy near half-integer ν in a wide range of N ≥ 2 in originally isotropic 2D systems.…”

“…Similar observations were made in wide GaAs/AlGaAs quantum wells with two occupied subbands. 21,22 However, we are not aware of any reports that B can induce significant anisotropy near half-integer ν in a wide range of N ≥ 2 in originally isotropic 2D systems.…”

“…[20][21][22] For example, Ref. 20 reported a strong anisotropy at ν = 4 of a 2DEG in Si/SiGe in a narrow range of tilt angles, with the hard axis along B .…”

“…Another class of B -induced anisotropies appears at integer ν, when two Landau levels are brought into coincidence [21][22][23]. For example, Ref.…”