Striped magnetic ground state on an ideal S = 2 Kagomé lattice
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Date
2017
Journal Title
Journal ISSN
Volume Title
Publisher
International Union of Crystallography
Abstract
We have used representational symmetry analysis of neutron powder diffraction data to determine the magnetic ground state of Fe4Si2Sn7O16. We recently reported a long-range antiferromagnetic (AFM) Néel ordering transition in this compound at TN = 3.0 K, based on magnetization measurements. [1] The only magnetic ions present are layers of high-spin Fe2+ (d6, S = 2) arranged on a perfect kagomé lattice (trigonal space group P-3m1). [2] Below TN = 3.0 K, the spins on 2/3 of these magnetic ions order into canted antiferromagnetic chains, separated by the remaining 1/3 which are geometrically frustrated and show no long-range ordered down to at least T = 0.1 K. Moessbauer spectroscopy shows that there is no static order on the latter 1/3 of the magnetic ions – i.e., they are in a liquid-like rather than a frozen state – down to at least 1.65 K. A heavily Mn-doped sample Fe1.45Mn2.55Si2Sn7O16 has the same ground state. Although the magnetic propagation vector k = (0, 1/2, 1/2) breaks hexagonal symmetry, we see no evidence for magnetostriction in the form of a lattice distortion within the resolution of our data. To the best of our knowledge, this type of magnetic order on a kagomé lattice has no precedent experimentally and has not been explicitly predicted theoretically. We will discuss the relationship between our experimental result and a number of theoretical models that predict symmetry breaking ground states for perfect kagomé lattices. © International Union of Crystallography
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Keywords
Neutron diffraction, Magnetism, Crystal lattices, Antiferromagnetism, Ground states, Spin
Citation
Ling, C. D., Allison, M., Schmid, S., Avdeev, M., Ryan, D., & Soehnel, T. (2017). Striped magnetic ground state on an ideal S = 2 Kagomé lattice. Presentation to to XXIV IUCr Congress, Hyderabad, India, 21-28 August 2017. In Acta Crystallographica Section A: Foundations and Advances, 73(a2), C1340. doi:10.1107/S2053273317082353