6.1.2 (ARO): Contacting the Quantum Anomalous Hall State
Abstract
Major Goals: Quantum Hall edges offer extremely promising prospects for exploring topological superconductivity. In the integer regime one expects to be able to generate chiral Majorana modes and localized Majorana excitations with non Abelian braiding statistics. There are however several key challenges in exploring this physics experimentally using the traditional materials exhibiting the quantum Hall effect. First, at filling factor one the ground state consists of spin polarized electrons and hence inducing superconductivity requires a p-type superconductor. Additionally, the large field needed to reach the quantum Hall regime limits the types of superconductors that one might be able to explore. To circumvent some of these challenges, we propose to explore the coupling of superconductivity to the quantum anomalous Hall effect. The quantum anomalous Hall effect occurs at zero magnetic field in thin topological insulators that are magnetically doped. The coupling between the top and bottom surface sates when the thickness is small leads to the gapping of the surface states leaving only edge conduction. The magnetic doping removes one of the chiral edge states resulting in a quantum anomalous Hall state. Such state occurs at zero magnetic field and hence alleviates much of the difficulty associated with coupling superconductivity to quantum Hall edges. Thus far studies of the anomalous quantized Hall effect were done in millimeter size hall bars with normal contacts that are unsuitable for exploring Josephson coupling. In this proposal we will develop micron size normal and superconducting contacts as well as optical and e-beam fabrication schemes that would pave the way towards exploring this phase in mesoscopic devices and the coupling of superconductivity and the quantum anomalous Hall effect. We will work on V doped and Cr doped (Bi, Sb)2 Te3 layers that have been shown to produce the strongest quantization of the quantized anomalous Hall state.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 29, 2021
- Accession Number
- AD1200952
Entities
People
- Amir Yacoby
Organizations
- Harvard University