Correlation-driven metallic topology

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.

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.

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.

To achieve these objectives, the versatile platform of heavy fermion compounds

will be used. Four different design principles - symmetry, emergence, engineered

platforms, and parameter tuning - will be followed, and 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.

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?

We expect the project to establish an emerging field, and provide guidance to a

larger community to boost progress.