Topopological Insulators with Half-Heusler structure

Project leaders: Prof. H.-J. Elmers, Prof. G. Schönhense, PD Dr. M. Jourdan,

Partially supported by the DFG via the priority program Topological Insulators (SPP 1666, El172/18-1) and via project Jo404/9-1.

Three dimensional topological insulators are insulating in the bulk, but strong spin-orbit coupling enables a special electronic structure with inverted bands resulting in the formation of a topologically protected single Dirac cone like surface state. As in such materials the orientation of the spins is fixed relative to the direction of a charge current carried by the surface state, its potential for spintronics applications is evident.

A class of materials where topological insulator compounds have been predicted are Half-Heuslers.  Generally consisting of nontoxic components suitable for industrial production processes, these represent ideal candidate materials for such applications.

We investigate the surface band structure of sputter deposited Half-Heusler thin films like YPtBi in-situ by Time of Flight-momentum microscopy. Very recently, we directly demonstrated the presence of a Dirac cone representing a topologically protected surface state together with only little additional spectral weight at EF due to other states (unpublished).