New Magnetic Interfaces for Quantum Phenomena
Abstract
This project is aimed at producing heterostructures between exfoliated two-dimensional materials and the surfaces of thin films grown by other techniques, and characterizing emergent quantum phenomena in the resultant hybrid materials. This project is inspired by recent experimental developments in the fabrication of exfoliated 2D heterostructures, in the synthesis of thin films as well as their characterization with high resolution spectroscopic probes. The project is also inspired by new theoretical developments in the topological properties of solids, especially as applied to superlattices.Four specific materials combinations are proposed under this project. The first of these is to combine monolayer or few-layer exfoliated, s-wave superconductors with magnetic films that have skyrmion textures. Theory predicts that under these conditions, triplet superconductivity can be induced in the vicinity of the skyrmion, and the confirmation of this prediction is the goal of this experiment. In practice, magnetic films produced by sputtering will be introduced into an apparatus capable of surface cleaning, exfoliation of monolayers and stacking of the monolayers onto the magnetic films all in UHV conditions. The hybrid heterostructure will be transferred via vacuum suitcase to a 0.3 K scanning tunneling microscope for spectroscopic investigation. Signatures of triplet superconductivity in the local spectra as well as the momentum dependence of the superconducting gap via quasiparticle interference experiments will both be used to probe the existence of the triplet state.The second materials combination that will be investigated is the coupling of 2D layers with the surface states of InAs grown by molecular beam epitaxy. The aim of this experiment will be to create a superlattice potential on the InAs surface state, causing the formation of flat sub-bands. InAs features tunable spin-orbit coupling with a significant Rashba component. This is a unique characteristic not available in known exfoliated 2D materials, and offers us an avenue to realize new topological phenomena by moire patterning of a 2D surface state with Rashba spin-orbit coupling. Properties of the moire patterned surface state will be investigated by STM spectroscopy and imaging.The third materials combination that will be investigated is the coupling of 2D exfoliated magnets with magnetic textures in thin film or patterned nanomagnets. 2D exfoliated magnets are a recently explored set of magnetic materials with a single crystal host material, unlike thin magnetic films. So far, uniform magnetization states have been probed in these materials. Our aim will be to use the magnetic textures in the underlying thin films to imprint textures into the 2D magnet. These textures will in-turn be used to study the fundamentals of electron scattering from domain walls and other textures in an otherwise crystalline magnet.The final materials combination that will be investigated is the combination of few layer graphitic substrates with cuprate high-Tc superconductors grown by molecular beam epitaxy. The aim of this experiment will be to study the nature of the superconductivity induced into the graphitic structures by proximity to the cuprate substrate. The graphitic substrates will include monolayer graphene as well as moire graphene structures such as twisted bilayer graphene, which feature large peaks in the density of states. The aim of the experiment will be to understand what the symmetry of the induced superconductivity is, and whether it is different from the d-wave order parameter of the underlying cuprate.Apart from the four experiments with novel materials described above, this project will also improve the state of the art of STM experiments on 2D materials in two ways.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 07, 2023
- Source ID
- FA95502110378
Entities
People
- Abhay Pasupathy
Organizations
- Air Force Office of Scientific Research
- Trustees of Columbia University in the City of New York
- United States Air Force