Tensor network analysis of the maple-leaf antiferromagnet spangolite

Abstract Spangolite (Cu6Al(SO4)(OH)12Cl ⋅ 3H2O) is a hydroxy-hydrated copper sulfate mineral with a one-seventh depleted triangular lattice of Cu2+ ions in each layer. Experimental measurements revealed a non-magnetic ground state at T ~ 8 K with magnetic properties dominated by dimerization. We pro...

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Main Authors: Philipp Schmoll, Harald O. Jeschke, Yasir Iqbal
Format: Article
Language:English
Published: Nature Portfolio 2025-08-01
Series:Communications Materials
Online Access:https://doi.org/10.1038/s43246-025-00904-1
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author Philipp Schmoll
Harald O. Jeschke
Yasir Iqbal
author_facet Philipp Schmoll
Harald O. Jeschke
Yasir Iqbal
author_sort Philipp Schmoll
collection DOAJ
description Abstract Spangolite (Cu6Al(SO4)(OH)12Cl ⋅ 3H2O) is a hydroxy-hydrated copper sulfate mineral with a one-seventh depleted triangular lattice of Cu2+ ions in each layer. Experimental measurements revealed a non-magnetic ground state at T ~ 8 K with magnetic properties dominated by dimerization. We propose a spatially anisotropic Heisenberg model for the Cu2+ spin-1/2 degrees of freedom on this geometrically frustrated and effectively two-dimensional maple-leaf lattice, featuring five symmetry inequivalent couplings with ferromagnetic bonds on hexagons and antiferromagnetic triangular bonds. The validity of the proposed Hamiltonian is demonstrated by state-of-the-art tensor network calculations, which can assess both the nature of the ground state as well as low-temperature thermodynamics, including the effects of a magnetic field. We provide theoretical support for a picture of a non-trivially correlated dimer ground state, which accounts for the appreciable reduction of the magnetic moment at high temperatures observed in experiment, thereby resolving a long-standing puzzle. We predict the static spin structure factor as well as the emergence of magnetisation plateaus at high values of an external magnetic field, explore the nature of the quantum states in them, and study their melting with increasing temperature.
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spelling doaj-art-91f06cc6b7c64a6e9f6a4990218e2e022025-08-20T04:03:02ZengNature PortfolioCommunications Materials2662-44432025-08-01611910.1038/s43246-025-00904-1Tensor network analysis of the maple-leaf antiferromagnet spangolitePhilipp Schmoll0Harald O. Jeschke1Yasir Iqbal2Freie Universität Berlin, Dahlem Center for Complex Quantum Systems and Institut für Theoretische PhysikResearch Institute for Interdisciplinary Science, Okayama UniversityDepartment of Physics and Quantum Centre of Excellence for Diamond and Emergent Materials (QuCenDiEM), Indian Institute of Technology MadrasAbstract Spangolite (Cu6Al(SO4)(OH)12Cl ⋅ 3H2O) is a hydroxy-hydrated copper sulfate mineral with a one-seventh depleted triangular lattice of Cu2+ ions in each layer. Experimental measurements revealed a non-magnetic ground state at T ~ 8 K with magnetic properties dominated by dimerization. We propose a spatially anisotropic Heisenberg model for the Cu2+ spin-1/2 degrees of freedom on this geometrically frustrated and effectively two-dimensional maple-leaf lattice, featuring five symmetry inequivalent couplings with ferromagnetic bonds on hexagons and antiferromagnetic triangular bonds. The validity of the proposed Hamiltonian is demonstrated by state-of-the-art tensor network calculations, which can assess both the nature of the ground state as well as low-temperature thermodynamics, including the effects of a magnetic field. We provide theoretical support for a picture of a non-trivially correlated dimer ground state, which accounts for the appreciable reduction of the magnetic moment at high temperatures observed in experiment, thereby resolving a long-standing puzzle. We predict the static spin structure factor as well as the emergence of magnetisation plateaus at high values of an external magnetic field, explore the nature of the quantum states in them, and study their melting with increasing temperature.https://doi.org/10.1038/s43246-025-00904-1
spellingShingle Philipp Schmoll
Harald O. Jeschke
Yasir Iqbal
Tensor network analysis of the maple-leaf antiferromagnet spangolite
Communications Materials
title Tensor network analysis of the maple-leaf antiferromagnet spangolite
title_full Tensor network analysis of the maple-leaf antiferromagnet spangolite
title_fullStr Tensor network analysis of the maple-leaf antiferromagnet spangolite
title_full_unstemmed Tensor network analysis of the maple-leaf antiferromagnet spangolite
title_short Tensor network analysis of the maple-leaf antiferromagnet spangolite
title_sort tensor network analysis of the maple leaf antiferromagnet spangolite
url https://doi.org/10.1038/s43246-025-00904-1
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