From dimensional reduction to tetramerization in mixed ferro-antiferro breathing pyrochlores
Abstract
We study the spin-1/2 nearest-neighbor Heisenberg model on the breathing pyrochlore lattice in the mixed ferro-antiferromagnetic regime, where one tetrahedral sublattice is antiferromagnetic and the other ferromagnetic. The classical ground-state manifold is then that of the nearest-neighbor face-centered-cubic (fcc) antiferromagnet built from composite tetrahedral moments. Classical Monte Carlo simulations and the self-consistent Gaussian approximation show that thermal order-by-disorder lifts its subextensive degeneracy and selects the collinear Type-I state with wave vector X=(1,0,0) through a strongly first-order transition. Pseudofermion functional renormalization group calculations for S=1/2 and S=1 reveal a nonmagnetic window adjacent to the decoupled antiferromagnetic-tetrahedron limit, beyond which X order reappears. Density matrix renormalization group calculations show that this window is not featureless: the antiferromagnetic tetrahedra develop nearly ideal tetramer correlations, with four bonds carrying ⟨Si·Sj⟩≃−1/2 and the two opposite bonds ≃+1/4, while the structure factor retains broad maxima at X. A third-order effective Hamiltonian in the tetrahedral-singlet manifold explains this: reversing the sign of the inter-tetrahedron coupling converts Tsunetsugu's dimer selection into a uniform tetramer selection, as confirmed by exact diagonalization. A dynamic high-temperature expansion traces how local tetrahedral excitations give way to low-energy X-centered spectral weight. Finally, we place density-functional parameters for eight structures of spin-3/2 breathing chromium thiospinels in the classical phase diagram. The mapping reproduces the k=(1,0,0) order of CuInCr4S8, accounts for the absence of order in LiGaCr4S8, and predicts Type-I order for LiInCr4S8.
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BibTeX
@misc{chatterjee2026from,
title = {{From dimensional reduction to tetramerization in mixed ferro-antiferro breathing pyrochlores}},
author = {Sourin Chatterjee and Kelvin Salou-Smith and Benedikt Schneider and Imre Hagymási and Arnaud Ralko and Johannes Reuther and Jeffrey G. Rau and Karlo Penc and Harald O. Jeschke and Ludovic D. C. Jaubert and Yasir Iqbal},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.30162},
eprint = {2609.30162},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.30162},
}
RIS
TY - UNPB
TI - From dimensional reduction to tetramerization in mixed ferro-antiferro breathing pyrochlores
AU - Sourin Chatterjee
AU - Kelvin Salou-Smith
AU - Benedikt Schneider
AU - Imre Hagymási
AU - Arnaud Ralko
AU - Johannes Reuther
AU - Jeffrey G. Rau
AU - Karlo Penc
AU - Harald O. Jeschke
AU - Ludovic D. C. Jaubert
AU - Yasir Iqbal
PY - 2026
DA - 2026/09/24
PB - arXiv
DO - 10.48550/arxiv.2609.30162
UR - https://arxiv.org/abs/2609.30162
AB - We study the spin-1/2 nearest-neighbor Heisenberg model on the breathing pyrochlore lattice in the mixed ferro-antiferromagnetic regime, where one tetrahedral sublattice is antiferromagnetic and the other ferromagnetic. The classical ground-state manifold is then that of the nearest-neighbor face-centered-cubic (fcc) antiferromagnet built from composite tetrahedral moments. Classical Monte Carlo simulations and the self-consistent Gaussian approximation show that thermal order-by-disorder lifts its subextensive degeneracy and selects the collinear Type-I state with wave vector X=(1,0,0) through a strongly first-order transition. Pseudofermion functional renormalization group calculations for S=1/2 and S=1 reveal a nonmagnetic window adjacent to the decoupled antiferromagnetic-tetrahedron limit, beyond which X order reappears. Density matrix renormalization group calculations show that this window is not featureless: the antiferromagnetic tetrahedra develop nearly ideal tetramer correlations, with four bonds carrying ⟨S_i·S_j⟩≃−1/2 and the two opposite bonds ≃+1/4, while the structure factor retains broad maxima at X. A third-order effective Hamiltonian in the tetrahedral-singlet manifold explains this: reversing the sign of the inter-tetrahedron coupling converts Tsunetsugu's dimer selection into a uniform tetramer selection, as confirmed by exact diagonalization. A dynamic high-temperature expansion traces how local tetrahedral excitations give way to low-energy X-centered spectral weight. Finally, we place density-functional parameters for eight structures of spin-3/2 breathing chromium thiospinels in the classical phase diagram. The mapping reproduces the k=(1,0,0) order of CuInCr_4S_8, accounts for the absence of order in LiGaCr_4S_8, and predicts Type-I order for LiInCr_4S_8.
ER -