Effective Spin-2 Quasi-particles at Linear Dispersive Five-fold Degenerate Points with Tunable Topological Chern Numbers

TL;DR

This paper proposes a theoretical design for realizing spin-2 quasi-particles at five-fold degenerate points with tunable topological Chern numbers in a cubic lattice system, advancing topological band theory.

Contribution

It introduces a model with linearly dispersive five-fold degenerate points involving spin-2 vectors and tensors, and demonstrates tunable topological properties via coupling adjustments.

Findings

Calculated Chern numbers for different couplings.

Designed a lattice model with five internal states.

Showed tunability of topological invariants.

Abstract

In this work, which is based on spin-2 vectors and traceless spin-2 tensors, an effective Hamiltonian is constructed with a linearly dispersive five-fold degenerate point with spin-2 vector-momentum couplings. For the model without spin-2 vector-tensor coupling, the topological Chern numbers of five bands are calculated as 4, 2, 0, -2, -4. After including spin-2 vector-tensor coupling, separate topological Chern numbers are obtained for different couplings. A cubic lattice of atoms with five internal states is designed to realize two five-fold degenerate points. The Chern numbers of the bands can be changed by tuning the coupling coefficient. In this work we propose a theoretical design to obtain spin-2 quasi-particles.