Strong and Tunable Spin–Orbit Coupling in a Two-Dimensional Hole Gas in Ionic-Liquid Gated Diamond Devices

• Published in: Nano letters Vol. 16; no. 6; pp. 3768 - 3773
• Main Authors: Akhgar, Golrokh, Klochan, Oleh, Willems van Beveren, Laurens H, Edmonds, Mark T, Maier, Florian, Spencer, Benjamin J, McCallum, Jeffrey C, Ley, Lothar, Hamilton, Alex R, Pakes, Christopher I
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08-06-2016
• Subjects: weak antilocalization; surface conductivity; diamond; spin−orbit splitting; 2DHG
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.6b01155

Hydrogen-terminated diamond possesses due to transfer doping a quasi-two-dimensional (2D) hole accumulation layer at the surface with a strong, Rashba-type spin–orbit coupling that arises from the highly asymmetric confinement potential. By modulating the hole concentration and thus the potential using an electrostatic gate with an ionic-liquid dielectric architecture the spin–orbit splitting can be tuned from 4.6–24.5 meV with a concurrent spin relaxation length of 33–16 nm and hole sheet densities of up to 7.23 × 1013 cm–2. This demonstrates a spin–orbit interaction of unprecedented strength and tunability for a 2D hole system at the surface of a wide band gap semiconductor. With a spin relaxation length that is experimentally accessible using existing nanofabrication techniques, this result suggests that hydrogen-terminated diamond has great potential for the study and application of spin transport phenomena.