Quantum spintronics is an active research field aiming at the development of semiconductor quantum devices with spin-based functionality. This field is witnessing an increasing interest in exploiting the spin degree of freedom of hole spin states, which can present a strong spin−orbit (SO) coupling, enabling electric-field driven spin manipulation and a reduced hyperfine interaction, favouring spin coherence. An international research team led by Maksym Myronov has demonstrated experimental evidence of ballistic hole transport in 1D quantum wires gate-defined in a strained Germanium quantum well (QW). At zero magnetic field, conductance plateaus at integer multiples of 2e2/h are observed. At finite magnetic field, the splitting of these plateaus by Zeeman effect reveals largely anisotropic g-factors with absolute values below 1 in the QW plane, and exceeding 10 out-of plane. This g-factor anisotropy is consistent with a heavy-hole character of the propagating valence-band states, which is in line with a predominant confinement in the growth direction. Remarkably, quantized ballistic conductance in device channels up to 600 nm long is observed. These findings mark an important step toward the realization of novel devices for applications in quantum spintronics.

• Publication: Nano Lett. 2018, 18, 4861−4865
• DOI: 10.1021/acs.nanolett.8b01457