Fractional form of the 0.7(2e2/h) feature

TL;DR

This paper reports the observation of spin transistor effects in a silicon-based quantum ring, highlighting fractional conductance oscillations due to Rashba spin-orbit interaction and the interplay of spin polarization.

Contribution

It presents the first experimental evidence of fractional Aharonov-Casher conductance oscillations in a silicon quantum well device, linking Rashba SOI to the 0.7 conductance feature.

Findings

Observation of 0.7(2e2/h) conductance feature due to spin effects

Detection of fractional Aharonov-Casher oscillations

Interplay of spin polarization and Rashba SOI influences conductance

Abstract

We present the first findings of the spin transistor effect in the Rashba gate-controlled ring embedded in the p-type self-assembled silicon quantum well that is prepared on the n-type Si (100) surface. The coherence and phase sensitivity of the spin-dependent transport of holes 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 and revealed by the Aharonov-Bohm (AB) and Aharonov-Casher (AC) conductance oscillations, respectively. Firstly, the amplitude and phase sensitivity of the 0.7(2e2/h) feature of the hole quantum conductance staircase revealed by the quantum point contact inserted in the one of the arms of the double-slit ring are found to result from the interplay of the spontaneous spin polarization and the Rashba spin-orbit interaction (SOI). Secondly, the values of the AC conductance oscillations caused by the Rashba SOI are found to take the fractional form with both the plateaus and steps as a function of the top gate voltage.