Hidden magnetic order in CuNCN

Abstract

We report a comprehensive experimental and theoretical study of the quasi-one-dimensional quantum magnet CuNCN. Based on magnetization measurements above room temperature as well as muon spin rotation and electron spin resonance measurements, we unequivocally establish the localized Cu+2-based magnetism and the magnetic transition around 70 K, both controversially discussed in the previous literature. Thermodynamic data conform to the uniform-spin-chain model with a nearest-neighbor intrachain coupling of about 2300 K, in remarkable agreement with the microscopic magnetic model based on density functional theory band-structure calculations. Using exact diagonalization and the coupled-cluster method, we derive a collinear antiferromagnetic order with a strongly reduced ordered moment of about 0.4 mu_B, indicating strong quantum fluctuations inherent to this quasi-one-dimensional spin system. We re-analyze the available neutron-scattering data, and conclude that they are not sufficient to resolve or disprove the magnetic order in CuNCN. By contrast, spectroscopic techniques indeed show signatures of long-range magnetic order below 70 K, yet with a rather broad distribution of internal field probed by implanted muons. We contemplate the possible structural origin of this effect and emphasize peculiar features of the microstructure studied with synchrotron powder x-ray diffraction.

17 pages, 17 figures, 1 table

References in corpus (15)

• The ALPS project release 1.3: open source software for strongly correlated systems
• Ground-state phases of the spin-1/2 J_1-J_2 Heisenberg antiferromagnet on the square lattice: A high-order coupled cluster treatment
• Coupled Cluster Treatment of the Shastry-Sutherland Antiferromagnet
• Frustrated spin-1/2 square lattice in the layered perovskite PbVO(3)
• Magnetic order in the S=1/2 two-dimensional molecular antiferromagnet, copper pyrazine perchlorate Cu(Pz)_2(ClO_4)_2
• Sr${}_2$Cu(PO${}_4$)${}_2$: A real material realization of the 1D nearest neighbor Heisenberg chain
• Influence of an inter-chain coupling on spiral ground-state correlations in frustrated spin-1/2 J1-J2 Heisenberg chains
• Single Crystal Growth, Crystallography, Magnetic Susceptibility, Heat Capacity, and Thermal Expansion of the Antiferromagnetic S = 1 Chain Compound CaV2O4
• Large quantum fluctuations in the strongly coupled spin-1/2 chains of green dioptase: a hidden message from birds and trees
• Unconventional Magnetism in a Nitrogen-Based Analogue of Cupric Oxide
• Ab initio modeling of Bose-Einstein condensation in Pb2V3O9
• Frustrated Quantum Antiferromagnets: Application of High-Order Coupled Cluster Method
• Antiferromagnetic spin-1/2 chains in (NO)Cu(NO3)3: a microscopic study
• Impurity-induced singlet breaking in SrCu2(BO3)2
• Ground-state long-range order in quasi-one-dimensional Heisenberg quantum antiferromagnets: High-order coupled-cluster calculations

Cited by in corpus (6)

• Magnetism of CuX2 frustrated chains (X = F, Cl, Br): the role of covalency
• Magnetism of coupled spin tetrahedra in ilinskite-type KCu${}_5$O${}_2$(SeO${}_3$)${}_2$Cl${}_3$
• Hidden orders in spin-orbit entangled correlated insulators
• Hidden Magnetic Order in Triangular-Lattice Magnet Li2MnTeO6
• Magnetic inhomogeneity in the copper pseudochalcogenide CuNCN
• c-a-ca Mean Field RVB Model of CuNCN Physics. Structure Manifestations of the RVB Transitions