MSE Seminar: Judy J. Cha, Yale University

Description

Topological Nanomaterials and Their Phase Transformations

Making topological materials into nanostructures can enhance the desirable topological surface states due to the increased surface-to-volume ratio [1].  Moreover, novel electronic states can emerge in the reduced dimensions such as the Majorana bound states at the ends of a one-dimensional (1D) topological superconductor.

In this talk, I will discuss our synthesis efforts on realizing 1D topological nanomaterials.  Examples include superconducting topological crystalline insulator SnTe nanowires, WTe₂ nanowires, and the recently reported triple-point topological metal MoP nanowires.  Josephson junction studies using SnTe nanowires as weak links suggest novel superconductivity that can arise in a multiband superconductor with momentum-conserving electron scattering [2].  In situ cryo-TEM experiments demonstrate a cubic-to-rhombohedral phase transformation and the emergence of ferroelectric domains in SnTe nanowires, meeting the condition for the necessary electron scattering.  Finally, I will present a fabrication method that can produce a large array of nanowires with a controlled diameter and aspect ratio, which can transform synthesis of 1D topological nanomaterials [3].

[1] Nat. Rev. Mater. 4, p.479 (2019).

[2] arXiv:1907.04199 (2019).

[3] Phys. Rev. Lett. 124, 036102 (2020).