Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
  • Rapid Communication

Electric-field dependent g-factor anisotropy in Ge-Si core-shell nanowire quantum dots

Matthias Brauns, Joost Ridderbos, Ang Li, Erik P. A. M. Bakkers, and Floris A. Zwanenburg
Phys. Rev. B 93, 121408(R) – Published 17 March 2016
PDFHTMLExport Citation
Abstract
Authors
Article Text
  • INTRODUCTION
  • GATE-DEFINED QUANTUM DOTS
  • ZEEMAN SPLITTING OF THE ORBITAL GROUND…
  • g-FACTOR ANISOTROPY
  • CONCLUSION
  • ACKNOWLEDGMENTS
    • References

    Abstract

    We present angle-dependent measurements of the effective g factor g☆ in a Ge-Si core-shell nanowire quantum dot. g☆ is found to be maximum when the magnetic field is pointing perpendicularly to both the nanowire and the electric field induced by local gates. Alignment of the magnetic field with the electric field reduces g☆ significantly. g☆ is almost completely quenched when the magnetic field is aligned with the nanowire axis. These findings confirm recent calculations, where the obtained anisotropy is attributed to a Rashba-type spin-orbit interaction induced by heavy-hole light-hole mixing. In principle, this facilitates manipulation of spin-orbit qubits by means of a continuous high-frequency electric field.

    • Figure
    • Figure
    • Figure
    • Received 20 December 2015
    • Revised 25 February 2016

    DOI:https://doi.org/10.1103/PhysRevB.93.121408

    ©2016 American Physical Society

    Physics Subject Headings (PhySH)

    1. Research Areas
    SpintronicsZeeman effect
    1. Physical Systems
    Quantum dots
    1. Techniques
    Atomic force microscopy
    Condensed Matter, Materials & Applied Physics

    Authors & Affiliations

    Matthias Brauns1,*, Joost Ridderbos1, Ang Li2,†, Erik P. A. M. Bakkers2,3, and Floris A. Zwanenburg1

    • 1NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
    • 2Department of Applied Physics, Eindhoven University of Technology, Postbox 513, 5600 MB Eindhoven, The Netherlands
    • 3QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands

    • *Corresponding author: m.brauns@utwente.nl
    • †Present address: Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Pingleyuan No. 100, 100024, Beijing, People's Republic of China.

    Article Text (Subscription Required)

    Click to Expand

    References (Subscription Required)

    Click to Expand
    Issue

    Vol. 93, Iss. 12 — 15 March 2016

    Reuse & Permissions
    Access Options
    Author publication services for translation and copyediting assistance advertisement

    Authorization Required

    Log In
    Other Options
    ×

    Images

    • Figure 1
      Figure 1

      (a) False-color atomic-force microscopy image of the device. (b) Schematic cross section displaying the p++−doped Si substrate (grey) with 200 nm of SiO2 (dark red), six bottom gates g1-g6 (light red), each ∼35 nm wide and with 100 nm pitch buried under 10 nm Al2O3 (yellow), on top of which the nanowire is placed (green) with ohmic contacts (0.5/50 nm Ti/Pd, blue). (c) Current I vs Vg4 with g3 and g5 forming tunnel barriers (Vg3=2060 mV, Vg5=2260 mV). Black curve is taken at VSD=1 mV, red curve at VSD=50 mV. (d) Numerical differential conductance dI/dVSD plotted vs VSD and Vg4 at the same barrier voltages as in (c).

      Reuse & Permissions
    • Figure 2
      Figure 2

      (a) Bias spectroscopy of the charge transition used for magnetospectroscopy measurements. The dI/dV color scale applies to all bias spectroscopies in this figure. (b) dI/dV vs VSD and B along the green line in (a). (c) ΔEZ extracted from (b) vs B together with a linear fit (red line) that yields g☆=2.7±0.1. (d) Bias spectroscopies measured at B=0 (upper panel), and B=1 T (lower panel). The green arrows indicate the spin-degenerate and spin-split orbital ground states. Measurements in Fig. 3 were taken along the blue line.

      Reuse & Permissions
    • Figure 3
      Figure 3

      (a) dI/dV plotted for different B⃗-field directions at constant B=1 T measured along the blue line in Fig. 2. Rotation of the magnetic field along (a) ϕ1 in the plane of the chip, (b) ϕ2 in the plane perpendicular to the nanowire axis, and (c) ϕ3 from the electric-field axis to the nanowire axis. (d) Line cuts taken from (a) at ϕ=−π (black circles) and ϕ=−π/2 (green circles) plotted together with the fit (green line as the sum of the dark green lines) for the ϕ=−π/2 line cut. (e) Line cuts taken from (b) at ϕ=π (black circles) and ϕ=−π/2 (blue circles) along with the respective fits (black and blue lines). (f) Summary of the measured g factors along the high-symmetry axes.

      Reuse & Permissions
    ×

    Sign up to receive regular email alerts from Physical Review B

    Log In

    Cancel
    ×

    Search

    Article Lookup

    Paste a citation or DOI
    Enter a citation
    ×