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Regular version of the site

Article

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

Physical Review Letters. 2017. Vol. 119. P. 047204-1-047204-5.
Smirnov A., Soldatov T. A., Petrenko O. A., Takata A., Kida T., Hagiwara M., Shapiro A. Y., Zhitomirsky M.

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 RbFe(MoO4)(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.