Realization of intrinsically broken Dirac cones in graphene via the momentum-resolved electronic band structure

TL;DR

This paper introduces a momentum-resolved band structure approach revealing that Dirac cones in graphene are intrinsically broken in momentum space, offering new insights into wave functions, ARPES spectra, and potential nanodevice design.

Contribution

It demonstrates that Dirac cones in graphene are intrinsically broken in momentum space and can be described using a smaller conceptual unit cell, enhancing understanding of electronic properties.

Findings

Dirac cones in graphene are intrinsically broken in momentum space.

A smaller conceptual unit cell describes the broken Dirac cones.

Momentum-resolved band structure improves interpretation of ARPES spectra.

Abstract

A way to represent the band structure that distinguishes between energy-momentum and energy-crystal momentum relationships is proposed upon the band-unfolding concept. This momentum-resolved band structure offers better understanding of the physical processes requiring the information of wave functions in momentum space and provides a good description of angle-resolved photoelectron spectroscopy (ARPES) spectra together with a still informative band structure. Following this approach, we demonstrate that Dirac cones in graphene are intrinsically broken in momentum space and can be described by a conceptual unit cell smaller than the primitive unit cell. This hidden degree of freedom can be measured by ARPES experiments as missing weight that is retrievable by probing the chirality and Berry phases by linearly and circularly polarized light. Having the energy-momentum relationship, we provide alternative understanding of the retrieved momentum intensity, that is, the retrieved momentum intensity is assisted with the properties of final states, not from the Dirac cones directly. The revealed broken Dirac cones and momenta supplied by the lattice give interesting ingredients for designing advanced nanodevices.