Metamorphic InAs1-xSbx/InAs1-ySby superlattices with ultra-low bandgap as a Dirac material

TL;DR

This paper demonstrates that ultra-low bandgap metamorphic InAsSb/InAsYb superlattices exhibit Dirac-like electron dispersion, with tunable Fermi velocity and effective mass, offering a versatile platform for exploring topological states.

Contribution

It provides experimental evidence of Dirac material properties in short-period metamorphic superlattices with ultra-low bandgap, highlighting their potential for topological studies.

Findings

Square root dependence of magneto-absorption peaks on magnetic field

Control of Fermi velocity via electron-hole overlap

Effective electron mass varies with superlattice period

Abstract

It was experimentally demonstrated that short-period metamorphic InAs1-xSbx/InAs1-ySby superlattices with ultra low bandgap have properties of a Dirac material. Cyclotron resonance and interband magneto-absorption peaks in superlattices with ultra-low bandgaps demonstrate a square root dependence on the magnetic field for a range up to 16 T (energy range up to 300meV). This directly indicates the linearity of the electron dispersion. The Fermi velocity can be controlled by varying the overlap between electron and hole states in the superlattice. The dependence of the cyclotron resonance energy on the magnetic field parallel to the superlattice plane demonstrates that the electron dispersion in the growth direction can be characterized by an effective mass of 0.028m0 in a superlattice with a period of 6 nm and 0.045m0 in a superlattice with a period of 7.5 nm. Extreme design flexibility makes the short-period metamorphic InAs1-xSbx/InAs1-ySby superlattice a new prospective platform for studying the effects of charge carrier chirality and topologically nontrivial states in structures with the inverted bandgaps.