2024/05/21 by Imre Hagymási, Hagymási, Imre, Nils Niggemann +3
Earth and Planetary Sciences · Physics and Astronomy · #Advanced Condensed Matter Physics #FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el) #earthquake and tectonic studies
paper · pdf · doi:10.48550/arxiv.2405.12745
openalex publication_date 2024/05/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We study the phase diagram of the antiferromagnetic J1-J2 Heisenberg model on the pyrochlore lattice with S=1 spins at zero and finite temperatures. We use a combination of complementary state-of-the-art quantum many-body approaches such as density matrix renormalization group (DMRG), density-matrix purification and pseudo-Majorana functional renormalization group (PMFRG). We present an efficient approach to preserve the applicability of the PMFRG for spin-1 systems at finite temperatures despite the inevitable presence of unphysical spin states. The good performance of our methods is first demonstrated for the nearest-neighbor pyrochlore Heisenberg model where the finite temperature behavior of the specific heat and uniform susceptibility show excellent agreement within PMFRG and density-matrix purification. Including an antiferromagnetic second neighbor coupling we find that the non-magnetic ground-state phase of the nearest neighbor model extents up to J2/J1 ∼ 0.02 within DMRG, beyond which magnetic \boldsymbolk=0 long-range order sets in. Our PMFRG calculations find the phase transition in a similar regime J2/J1∼ 0.035(8) which, together with the DMRG result, provides a strong argument for the existence of a small but finite non-magnetic ground-state phase in the spin-1 pyrochlore Heisenberg model. We also discuss the origin of discrepancies between different versions of the functional renormalization group concerning the location of this phase transition.