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arXiv · 2510.12613

Quantum Spin Singlet and Classical Néel-Ordered Ground States in MoX3 (X = I, Br) Spin-3/2 Dimerized Antiferromagnetic Chain Crystals

Jordan Teeter·Topojit Debnath·Harshil Goyal·Md Sabbir Hossen Bijoy·Maedeh Taheri·Nicholas Sesing·Fariborz Kargar·Kirill Shtengel·Tina Salguero·Roger K. Lake·Alexander A. Balandin
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Abstract

We report that MoX3 (X = I, Br) are rare van der Waals materials that exhibit signatures of both quantum spin chains with a spin singlet ground state and classical Neel order. Bulk single crystals grown by chemical vapor transport exhibit classical antiferromagnetic ground states with a transition temperature of ~40 K as revealed by susceptibility and specific heat measurements. Above 40 K, the susceptibilities show the large, broad peaks associated with a quantum spin-singlet ground state and large singlet-triplet gaps of 21 meV and 25 meV. Monte Carlo simulations, density matrix renormalization-group calculations for finite spin-3/2 chains, and density functional theory reproduce the experimental behavior, confirming the interplay between strong one-dimensional intrachain and weak three-dimensional interchain couplings. MoX3 offers a unique platform for exploring quantum magnetism and magnetic excitations at the atomic chain limit, as these materials combine a 1D van der Waals motif, spin chain behavior, and classical interchain order.

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Jordan Teeter, Topojit Debnath, Harshil Goyal, Md Sabbir Hossen Bijoy, Maedeh Taheri, Nicholas Sesing, Fariborz Kargar, Kirill Shtengel, Tina Salguero, Roger K. Lake, Alexander A. Balandin. 2025-10-14. Quantum Spin Singlet and Classical Néel-Ordered Ground States in MoX3 (X = I, Br) Spin-3/2 Dimerized Antiferromagnetic Chain Crystals. https://arxiv.org/abs/2510.12613

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