Order by Quenched Disorder in the Model Triangular Antiferromagnet RbFe(MoO4)2

Abstract

(2017) Order by quenched disorder in the model triangular antiferromagnet RbFe(MoO4)2. Physical Review Letters, 119 (4). 047204. Permanent WRAP URL:http://wrap.warwick.ac.uk/91153 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. We observe a disappearance of the 1=3 magnetization plateau and a striking change of the magnetic configuration under a moderate doping of the model triangular antiferromagnet RbFeðMoO 4 Þ 2 . The reason is an effective lifting of degeneracy of mean-field ground states by a random potential of impurities, which compensates, in the low-temperature limit, the fluctuation contribution to free energy. These results provide a direct experimental confirmation of the fluctuation origin of the ground state in a real frustrated system. The change of the ground state to a least collinear configuration reveals an effective positive biquadratic exchange provided by the structural disorder. On heating, doped samples regain the structure of a pure compound, thus allowing for an investigation of the remarkable competition between thermal and structural disorder. Publisher

Survival of itinerant excitations and quantum spin state transitions in YbMgGaO4 with chemical disorder

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