MSE Seminar Speaker: Colin Heikes, NSIT Center for Neutron Research
Friday, March 2, 2018
2110 Chem/Nuc Engineering Building
Speaker: Colin Heikes, NRC Postdoc Fellow @ NIST Center for Neutron Research
Title: Pressure and strain dependent control of structure and band topology in the superconducting type-II Weyl semimetal candidate MoTe2
The reported pressure dependent superconductivity of the proposed type-II Weyl semimetal MoTe2 has led to speculation about the possibility of a topologically non-trivial superconducting state in this material. The interplay between broken inversion symmetry through a structural phase transition, superconductivity, and reported non-trivial band topology in this system offers a playground for potential interesting and new materials physics. A key question about the topology of this superconducting state is the evolution of the crystal structure of MoTe2 at pressures and temperatures relevant for superconductivity, as the non-centrosymmetric Td orthorhombic phase is needed for the Weyl state and non-centrosymmetric superconductors themselves are interesting for supporting proposed Majorana modes. We have grown single crystals of MoTe2, and using a combination of elastic neutron scattering, magnetotransport, and spectroscopic techniques over a range of thermodynamic phase space. I will show that superconductivity can live within both centrosymmetric, non-centrosymmetric, and mixed structure phase states. I will also show that the application of pressure and strain allows us to control this state, and thus likely control the band topology of a superconductor.
Colin Heikes is a NRC Postdoctoral Fellow at the NIST Center for Neutron Research (NCNR), focusing on structure and magnetism in strongly correlated materials and quantum materials such as complex oxides and transition metal dichalcogenides. Colin received his B.S. in Materials Science and Engineering from UMD in 2008, and his PhD in Materials Science and Engineering from Cornell University in May 2015. While at Cornell, Colin studied low temperature magneto-optical properties of complex oxides and two-dimensional systems like transition metal dichalcogenides, as well as the growth of complex oxide thin-films and heterostructures using reactive oxide molecular beam epitaxy. Colin’s current research interests focus on the interplay between strain and interface engineering in multiferroic thin films, as well as the importance of ground state nuclear structure and defects to emergent quantum ground states in correlated electron materials.