Order by Quenched Disorder in the Model Triangular Antiferromagnet RbFe(MoO_{4})_{2}

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(MoO_{4})_{2}. The reason is an effective lifting of degeneracy of mean-field ground states by a random potential of imp...

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Veröffentlicht in:Physical review letters 2017-07, Vol.119 (4), p.047204-047204
Hauptverfasser: Smirnov, A I, Soldatov, T A, Petrenko, O A, Takata, A, Kida, T, Hagiwara, M, Shapiro, A Ya, Zhitomirsky, M E
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Sprache:eng
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Zusammenfassung: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(MoO_{4})_{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.
ISSN:1079-7114
DOI:10.1103/PhysRevLett.119.047204