Details

Autor(en) / Beteiligte

• Derzhko, Oleg
• Schnack, Jürgen
• Dmitriev, Dmitry V.
• Krivnov, Valery Ya
• Richter, Johannes

Titel

Flat-band physics in the spin-1/2 sawtooth chain

Ist Teil von

• The European physical journal. B, Condensed matter physics, 2020-08, Vol.93 (8), Article 161

Ort / Verlag

Berlin/Heidelberg: Springer Berlin Heidelberg

Erscheinungsjahr

2020

Quelle

SpringerLink

Beschreibungen/Notizen

• We consider the strongly anisotropic spin-1/2 XXZ model on the sawtooth-chain lattice with ferromagnetic longitudinal interaction J zz = Δ J and aniferromagnetic transversal interaction J xx = J yy = J > 0. At Δ = −1∕2 the lowest one-magnon excitation band is dispersionless (flat) leading to a massively degenerate set of ground states. Interestingly, this model admits a three-coloring representation of the ground-state manifold [H.J. Changlani et al., Phys. Rev. Lett. 120 , 117202 (2018)]. We characterize this ground-state manifold and elaborate the low-temperature thermodynamics of the system. We illustrate the manifestation of the flat-band physics of the anisotropic model by comparison with two isotropic flat-band Heisenberg sawtooth chains. Our analytical consideration is complemented by exact diagonalization and finite-temperature Lanczos method calculations. Graphical abstract