Topological superconductivity and induced phase transitions in strained Heusler membranes and twisted bilayers
Abstract
This proposal seeks to tune the complex interplay between Weyl fermions, Kondo interactions, and novel j=3/2 superconductivity in single-crystalline membranes of the rare earth Heusler compounds RPtBi. These materials are predicted to host rich phenomena from competing interactions; however, a fundamental understanding remains elusive due to the limited tunability of bulk crystals and the low superconducting transition temperature Tc ~ 1 K), which preclude the use of most spectroscopic probes in the superconducting state. In the proposed work, we will use extreme anisotropic strain and interfacial coupling in single crystalline Heusler membranes and heterostructures, to enhance Tc and measure the properties via angle-resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy (STM) and magnetotransport. We hypothesize that the extreme anisotropic strain states enabled by freestanding membranes, which we have recently synthesized by graphene-mediated epitaxy, will enable us to manipulate the band degeneracies, orbital overlaps, and ultimately, the balance of superconductivity, Kondo interactions, and Weyl states in these materials. Interfacing the RPtBi membranes with a magnetic shape memory alloy (e.g. the Heusler Ni2MnGa), will enable us to induce martensitic phase transitions in the RPtBi layer, and exploit the unprecedentedly large 15% strains to induce dramatic properties changes in response to changes in temperature or applied magnetic fields. We will also tune the strong correlations via Moire twist in incommensurate superlattices of these materials, that form spontaneously due to the weak Van der Waals decoupling of the graphene interlayer. The impact of this work will be to establish a new platform for flexible quantum materials membranes, for future Air Force applications in sensing and quantum information. Extreme strain states, Moire twist, and coupling structural phase transitions to topological, magnetic, and electronic properties, provide new handles for tuning quantum materials in membrane form. The concepts developed here are applicable to materials systems beyond Heusler compounds.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 21, 2022
- Source ID
- FA95502110127XX0
Entities
People
- Jason K Kawasaki
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Wisconsin System