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Magnetic order in the quasi-one-dimensional Ising system RbCoCl3

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Hänni N. P., Sheptyakov D., Mena M., Hirtenlechner E., Keller L., Stuhr U., Regnault L.-P., Medarde M., Cervellino A., Rüegg Ch., Normand B., Krämer K. W.,
Project New materials for honeycomb-lattice and single-ion magnets
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Original article (peer-reviewed)

Journal Physical Review B
Volume (Issue) 103(9)
Page(s) 094424 - 094424
Title of proceedings Physical Review B
DOI 10.1103/physrevb.103.094424


In RbCoCl3, the magnetic Co2+ ions form weakly coupled Ising chains arranged on a triangular lattice. We have investigated the structure and magnetism in RbCoCl3 by high-resolution x-ray diffraction and neutron scattering measurements on powder and single-crystal samples between 1.5 and 300 K. Upon cooling, the Co2+ spins develop one-dimensional antiferromagnetic correlations along the chain axis (c axis) below 90 K. Below the first Néel temperature, TN1 = 28K, a partial three-dimensional magnetic order sets in, with propagation vector k1 = (1/3, 1/3, 1), the moments aligned along the c axis, and every third chain uncorrelated from its neighbors. Only below a second magnetic phase transition at TN2 = 13K does the system achieve a fully ordered state, with two additional propagation vectors: k2 = (0, 0, 1) establishes a “honeycomb” c-axis order, in which one third of the chains are subject to a strong effective mean field due to their neighbors whereas two thirds experience no net field, while k3 = (1/2, 0, 1) governs a small, staggered, in-plane ordered moment. We conclude that RbCoCl3 is an excellent material to study the physics of Ising chains in a wide variety of temperature-controlled environments, and our results build an important foundation for the accurate interpretation of the spin dynamics measured in each case.