Symmetry breaking and competing valence bond states in the star lattice Heisenberg antiferromagnet

Ghosh P, Koziol J, Nyckees S, Schmidt KP, Mila F (2025)

Publication Type: Journal article

Publication year: 2025

Journal

Physical Review B American Physical Society

Book Volume: 112

Pages Range: 1444231-14442311

Journal Issue: 14

DOI: 10.1103/nbjt-hlvx

Abstract

We investigate the ground state phase diagram of the spin-1/2 antiferromagnetic Heisenberg model on the star lattice using infinite projected entangled pair states (iPEPS) and high-order series expansions. The model includes two distinct couplings: Jd on the dimer bonds and Jt on the trimer bonds. While it is established that the system hosts a valence bond solid (VBS) phase for Jd ≥ Jt, the ground state phase diagram for Jd < Jt has remained unsettled. Our iPEPS simulations uncover a first-order phase transition at Jd/Jt ≈ 0.18, significantly lower than previously reported estimates. Beyond this transition, we identify a close competition between two valence bond crystal (VBC) states; a columnar VBC and a √ 3 × √ 3 VBC, with the latter consistently exhibiting lower energy √ across all finite bond dimensions. The high-order series expansion supports this by finding that the 3 × √ 3 VBC state indeed becomes energetically favorable, but only at sixth order in perturbation theory, revealing the subtle nature of the competition between candidate states.

Authors with CRIS profile

Jan Koziol Lehrstuhl für Theoretische Physik Kai Phillip Schmidt Professur für Theoretische Physik

Involved external institutions

École Polytechnique Fédérale de Lausanne (EPFL) CH Switzerland (CH)

How to cite

APA:

Ghosh, P., Koziol, J., Nyckees, S., Schmidt, K.P., & Mila, F. (2025). Symmetry breaking and competing valence bond states in the star lattice Heisenberg antiferromagnet. Physical Review B, 112(14), 1444231-14442311. https://doi.org/10.1103/nbjt-hlvx

MLA:

Ghosh, Pratyay, et al. "Symmetry breaking and competing valence bond states in the star lattice Heisenberg antiferromagnet." Physical Review B 112.14 (2025): 1444231-14442311.

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