Phase and amplitude response of the '0.7 feature' caused by holes in silicon one-dimensional wires and rings
We present findings for the 0.7(2e2/h) feature in the hole quantum conductance staircase that is caused by silicon one-dimensional channels prepared by the split-gate method inside the p-type silicon quantum well (SQW) on the n-type Si(100) surface. Firstly, the interplay of the spin depolarization with the evolution of the 0.7(2e2/h) feature from the e2/h to 3/2 e2/h values as a function of the sheet density of holes is revealed by the quantum point contact connecting two 2D reservoirs in the p-type SQW. The 1D holes are demonstrated to be spin polarized at low sheet density, because the 0.7(2e2/h) feature is close to the value of 0.5(2e2/h) that indicates the spin degeneracy lifting for the first step of the quantum conductance staircase. The 0.7(2e2/h) feature is found to take, however, the value of 0.75(2e2/h) when the sheet density increases, thereby giving rise to the spin depolarization of the 1D holes. Secondly, the amplitude and phase sensitivity of the 0.7(2e2/h) feature are studied by varying the value of the external magnetic field and the top-gate voltage that are applied perpendicularly to the plane of the double-slit ring embedded in the p-type SQW, with the extra quantum point contact inserted in the one of its arms. The Aharonov-Bohm and the Aharonov-Casher conductance oscillations obtained are evidence of the interplay of the spontaneous spin polarization and the Rashba spin-orbit interaction (SOI) in the formation of the 0.7(2e2/h) feature. Finally, the variations of the 0.7(2e2/h) feature caused by the Rashba SOI are found to take in the fractional form with both the plateaus and steps as a function of the top-gate voltage.
Journal of Physics Condensed Matter
- Pub Date:
- April 2008
- Condensed Matter - Mesoscopic Systems and Quantum Hall Effect;
- Condensed Matter - Strongly Correlated Electrons
- J.Phys.: Condens.Matter 20 (2008) 164202