Descripción del proyecto
Las novedosas propiedades conductoras del bismuto
El ámbito de los aislantes topológicos es uno de los más interesantes de la física de la materia condensada. La mayor parte de este nuevo estado de materia cuántica es aislante; la corriente solo se transmite a través de la superficie y prácticamente sin disipación. El proyecto BALLISTOP, financiado con fondos europeos, investigará la carga y las corrientes de espín de aislantes topológicos de segundo orden. Esta nueva categoría de materiales topológicos incluye cristales en 3D como el bismuto, que tiene novedosas propiedades conductoras en los bordes en lugar de presentarlas de forma general o en la superficie. Los investigadores también valorarán la naturaleza balística de los estados de bordes helicoidales en 1D de muestras de bismuto. Una espectroscopia de efecto túnel les permitirá observar partículas de fermiones de Majorana en partículas de superconductores/bismuto. Este trabajo allanará el camino hacia la identificación de nuevos aislantes topológicos de primer orden.
Objetivo
One of the greatest recent achievement in Condensed matter physics is the discovery of a new class of materials, Topological Insulators (TI), whose bulk is insulating, while the edges conduct current in a quasi-ideal way. In particular, the 1D edges of 2DTI realize the Quantum Spin Hall state, where current is carried dissipationlessly by two counter-propagating ballistic edge states with a spin orientation locked to that of the propagation direction (a helical edge state). This opens many possibilities, ranging from dissipationless charge and spin transport at room temperature to new avenues for quantum computing. We propose to investigate charge and spin currents in a newly discovered class of TIs, Second Order Topological Insulators (SOTIs), i.e. 3D crystals with insulating bulk and surfaces, but perfectly conducting (topologically protected) 1D helical “hinge” states. Bismuth, despite its well-known semimetallic character, has recently been shown theoretically to belong to this class of materials, explaining our recent intriguing findings on nanowires. Our goal is to reveal, characterize and exploit the unique properties of SOTIs, in particular the high velocity, ballistic, and dissipationless hinge currents. We will probe crystalline bismuth samples with refined new experimental tools. The superconducting proximity effect will reveal the spatial distribution of conduction paths, and test the ballisticity of the hinge modes (that may coexist with non-topological surface modes). High frequency and tunnel spectroscopies of hybrid superconductor/Bi circuits will probe their topological nature, including the existence of Majorana modes. We will use high sensitivity magnetometers to detect the orbital magnetism of SOTI platelets, which should be dominated by topological edge currents. Lastly, we propose to detect the predicted equilibrium spin currents in 2DTIs and SOTIs via the generated electric field, using single electron transistors-based electrometers.
Ámbito científico
- natural sciencesphysical sciencescondensed matter physics
- natural scienceschemical sciencesinorganic chemistrypost-transition metals
- natural sciencesphysical scienceselectromagnetism and electronicsspintronics
- natural sciencesphysical scienceselectromagnetism and electronicssuperconductivity
- natural sciencesphysical sciencesopticsspectroscopy
Palabras clave
Programa(s)
Régimen de financiación
ERC-ADG - Advanced GrantInstitución de acogida
75794 Paris
Francia