Project description
A step closer to the first practical 3D topological insulator device
Topological insulators are exotic states of matter that behave as an insulator in their interior, but their surface contains conducting states, meaning that electrons can only move along the material surface. Electron transport in 3D topological insulators is dominated by bulk carriers that limit their potential to be used in modern spintronic devices and applications. The EU-funded MATTER project will provide a route around this barrier by following a nanoparticle design approach based on early stage sintering. Experimental work will be complemented by spectroscopic characterisation of nanoparticle properties as well as theoretical work on transport modelling. The project aims to demonstrate the first practical macroscopic quantum transport devices that utilise the electronic properties of surface states.
Objective
Ever since the discovery of topological surface states in three-dimensional (3D) topological insulators (TI), this fascinating physics has thrilled scientists. While arguable the transport properties of 3D TIs are of utmost importance for potential applications, they are extremely difficult to characterize, yet utilize for devices. The reason is that transport in those materials is always dominated by bulk carriers. Within this proposed research project, I will overcome the problem of bulk carrier domination conceptually by a nanoparticle-based materials’ design of interrupted early stage sintering. By this interrupted early stage sintering approach, I compact 3D TI nanoparticles at mild temperature and low pressure. The obtained highly porous macroscopic sample features a carrier density of the surface states in the order of 1018 cm-3, hence in a comparable order of magnitude as the bulk carrier density. Further, the interruptedly sintered nanoparticles impose energetic barriers for the transport of bulk carriers (hopping transport), while the connected surfaces of the nanoparticles provide a 3D percolation path for surface carriers. Within the preliminary work, my group tuned interruptedly sintered nanoparticles into a transport regime completely dominated by the surface states.
Within this project, nanoparticle-based macroscopic 3D TI materials will be developed towards test structures for devices. Their properties will be tailored by the nanoparticle synthesis (Objective 1) and the materials processing of interrupted early stage sintering (Objective 2). This is complemented by an in-depth characterization of the transport as well as spectroscopic properties and data modelling (Objective 3). My group will use this know-how for the fabrication of test devices (Objective 4). This combination will provide the first macroscopic quantum transport devices that utilize the unique electronic properties of surface states, overcoming the problem of bulk carrier domination
Fields of science
Programme(s)
Funding Scheme
ERC-COG - Consolidator GrantHost institution
45141 Essen
Germany