| AVS 64th International Symposium & Exhibition | |
| Electronic Materials and Photonics Division | Monday Sessions |
| Session EM+MI+TF-MoM |
| Session: | Growth, Electronic, and Magnetic Properties of Heusler Compounds |
| Presenter: | Jason Kawasaki, University of Wisconsin - Madison |
| Authors: | J. Kawasaki, University of Wisconsin - Madison A. Janotti, University of Delaware C.J. Palmstrøm, University of California at Santa Barbara |
| Correspondent: | Click to Email |
Half Heusler compounds (composition ABC) show great promise for the development of earth abundant thermoelectrics, half metallic ferromagnets for spin injection, and topological heterostructures. In these applications, the electronic structure of surfaces and interfaces are critical to materials performance. However, little is known about how and why the surfaces of these materials reconstruct or their direct effect on electronic properties. Using a combination of molecular beam epitaxy, angle resolved and core level photoemission, scanning tunneling microscopy, and density functional theory (DFT), we investigate the stability, reconstructions, and electronic surface states on the (001) surfaces of CoTiSb, NiTiSn, and FeVSb. These compounds are representative of a large class of 18 valence electron Half Heuslers that are expected to be semiconducting. We find that reconstructions in these compounds are characterized by C site (group IV or V) dimerization, as in III-V semiconductors, and this dimerization coincides with B site vacancies at the surface. We explain these trends using a simple electron counting model, and predictions from the model are in good agreement with both the experimental data and with DFT calculations. Our combined theoretical and experimental studies provide a rationale for understanding and controlling reconstructions and resultant electronic surface states in Heuslers.