Giant g factor tuning of long-lived electron spins in Ge

Abstract

Control of electron spin coherence via external fields is fundamental in spintronics. Its implementation demands a host material that accommodates the highly desirable but contrasting requirements of spin robustness to relaxation mechanisms and sizeable coupling between spin and orbital motion of charge carriers. Here we focus on Ge, which, by matching those criteria, is rapidly emerging as a prominent candidate for shuttling spin quantum bits in the mature framework of Si electronics. So far, however, the intrinsic spin-dependent phenomena of free electrons in conventional Ge/Si heterojunctions have proved to be elusive because of epitaxy constraints and an unfavourable band alignment. We overcome such fundamental limitations by investigating a two dimensional electron gas (2DEG) confined in quantum wells of pure Ge grown on SiGe-buffered Si substrates. These epitaxial systems demonstrate exceptionally long spin relaxation and coherence times, eventually unveiling the potential of Ge in bridging the gap between spintronic concepts and semiconductor device physics. In particular, by tuning spin-orbit interaction via quantum confinement we demonstrate that the electron Landé g factor and its anisotropy can be engineered in our scalable and CMOS-compatible architectures over a range previously inaccessible for Si spintronics.

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Cited by in corpus (13)

• The germanium quantum information route
• Particle-hole symmetry protects spin-valley blockade in graphene quantum dots
• Carrier and Spin Coherent Dynamics in Strained Germanium-Tin Semiconductor on Silicon
• Optimized micromagnet geometries for Majorana zero modes in low g-factor materials
• Intersubband transition engineering in the conduction band of asymmetric coupled Ge/SiGe quantum wells
• Magneto-optical determination of the carrier lifetime in coherent Ge(1-x)Sn(x)/Ge heterostructures
• Photoluminescence study of interband transitions in few-layer, pseudomorphic, and strain-unbalanced Ge/GeSi multiple quantum wells
• Chirality and intrinsic dissipation of spin modes in two-dimensional electron liquids
• Quantum spin Hall phase in GeSn heterostructures on silicon
• Emergent flat band lattices in spatially periodic magnetic fields
• Optical manipulation of the Rashba effect in germanium quantum wells
• Phase-controlled minimal Kitaev chain in multiterminal Josephson junctions
• Optical spin pumping in silicon