Correlation-driven metallic topology

Introduction

Developments in the past decade have shaped the term topological quantum matter. In the solid state, much progress has been made on non- and weakly-interacting systems and correlated insulators, but gapless topological phases governed by strong correlations are a completely open challenge. They are of great interest because a wealth of new quantum phases with new properties and functionalities are expected.

Recent Discoveries

The PI and her collaborators have recently discovered one such phase - the Weyl-Kondo semimetal - and brought to light its extreme topological responses as well as the feasibility of genuine topology control by external parameters. This sets the stage for the present project.

Project Objectives

In CorMeTop, new correlation-driven gapless topological phases shall be discovered and design principles for such phases established. New signatures of these phases shall be revealed and their potential for quantum devices assessed.

Methodology

To achieve these objectives, the versatile platform of heavy fermion compounds will be used. Four different design principles will be followed:

1. Symmetry
2. Emergence
3. Engineered platforms
4. Parameter tuning

A combination of recently established and entirely new experimental probes will be used. The basis for these studies will be high-quality bulk single crystals and thin films grown by molecular beam epitaxy.

Research Questions

Among the questions to be addressed are:

• To which extent does symmetry dictate the fate of topological states in the limit of strong correlations?
• What is the connection between quantum criticality or other emergent phenomena, long-range entanglement, and topology?
• Can entirely new platforms based on heavy fermion systems stabilize robust and even braidable Majorana bound states?
• Which theoretical parameters control topology and how can one vary them experimentally?
• Which functionalities bear potential for quantum applications?

Expected Outcomes

We expect the project to establish an emerging field and provide guidance to a larger community to boost progress.