| AVS 55th International Symposium & Exhibition | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM-TuA |
| Session: | Complex and Multifunctional Oxides |
| Presenter: | M. Gajdardziska-Josifovska, University of Wisconsin – Milwaukee |
| Authors: | M. Gajdardziska-Josifovska, University of Wisconsin – Milwaukee P. Dey, University of Wisconsin – Milwaukee K. Pande, University of Wisconsin – Milwaukee A. Celik-Aktas, University of Wisconsin – Milwaukee S.H. Cheung, University of Wisconsin – Milwaukee M. Weinert, University of Wisconsin – Milwaukee S.A. Chambers, Pacific Northwest National Laboratory |
| Correspondent: | Click to Email |
The most fundamental differences between oxide surfaces and those of metals and elemental semiconductors arise from the strong ionic character of the metal-oxygen bond, presenting opportunities to use polarity in design of novel oxide hetero-interfaces. For example, controlled growth of hematite and magnetite films has been a subject of intense studies inspired by their many technological applications in catalysis, gas sensing, sequestration of toxic metals, and magnetic devices. Surface and interface polarities add novel and desirable properties to these complex multi-functional oxide materials. In this work we integrate experimental and theoretical methods to study the atomic structure and electronic properties of hematite films grown on unreconstructed hydrogen-stabilized and on reconstruction stabilized polar oxide surfaces. We find that different modes of polar surface stabilization have profound effects on the growth mode, phase composition and magnetic properties of polar hematite films grown by OPA-MBE on magnesia and alumina single crystal substrates. Growth on reconstruction stabilized magnesia results in formation of an interfacial magnetite-like phase that offers a new way to create materials of interest in spintronics. This polarity-induced self-organized magnetite buffer persists after growth, in contrast to the transient maghemite detected by recent in-situ studies of the early stage of growth on unreconstructed sapphire surfaces. Indeed, pure phase Fe2O3 (0001) that is macroscopically antiferromagnetic is obtained on the hydrogen stabilized unreconstructed MgO(111) and Al2O3(0001) substrates. Theoretical modeling by DFT predicts unusual ferrimagnetic properties at the atomically abrupt α-Fe2O3 (0001)/MgO(111)-(1x1) interfaces.