TOP-down Superlattice engineering of 2D solid-state quantum matter

Introduction

Periodic potentials superimposed onto an atomic crystal allow for enhanced electronic correlations in a broad class of materials, from semiconductors to semimetals, if the spatial period of the potential becomes comparable to the Fermi wavelength of electrons. In this regime, the external superlattice potential creates tailored electronic minibands with new functionality.

Enhanced Electronic Behavior

By concentrating the density of states into van Hove singularities, superlattices can ultimately lead to flat bands, where complex correlated electronic behavior emerges already at moderate temperatures. Recent work has evidenced that lithographically defined superlattices in 2D van der Waals materials can achieve the necessary, close-to-atomistic precision to access this regime.

Project Overview

At this point, 2DTopS proposes a concerted effort to radically expand the concept of top-down superlattice engineering in 2D van der Waals materials and to explore the emerging physics.

Objectives

1. Generalize top-down fabrication of flat bands to dramatically enhance correlations in a broad class of materials, including:

   • Semiconductors
   • Semimetals with strong spin-orbit coupling
   • Topological semimetals

2. Leverage the polarizability of low-symmetry 2D materials to electronically and periodically modulate spin-orbit coupling, which has been theorized to enable unprecedented spin functionality.

Characterization and Tools

While the equilibrium Fermi surface and phase diagram will be characterized by magnetotransport, I will further establish light-matter coupling in solid-state superlattices as a complementary tool to interrogate:

• Symmetries
• Non-equilibrium dynamics of resonant interband transitions between flat bands, which are predicted to be intrinsically non-semiclassical but rather given by quantum geometric properties of the bands.

Conclusion

2DTopS bears potential for a paradigm shift in 2D materials research by harnessing close-to-atomistic top-down nanofabrication to access artificial quantum phases.