Critical slowing down near the multiferroic phase transition in MnWO4.
Critical slowing down near the multiferroic phase transition in MnWO4.
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DOI：
10.1103/physrevlett.114.037204
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发表时间：
2014-08
影响因子：
8.6
通讯作者：
D. Niermann;C. Grams;P. Becker;L. Bohatý;H. Schenck;J. Hemberger
中科院分区：
文献类型：
--
作者：
D. Niermann;C. Grams;P. Becker;L. Bohatý;H. Schenck;J. Hemberger
利用宽带介电谱研究了多铁性手征反铁磁体MnWO {4}的磁电动力学。在T_{N2}= 12.6 K的多铁性相变之上，我们观察到了类似于正则铁电体中软模行为的相应磁电涨落的临界慢化。这种电场驱动的激发比普通的声子模式携带更少的光谱权重。此外，该模式的临界减速与大于1的指数成比例，这是预期的磁性二阶相变的情况。因此，所研究的动力学必须被解释为软化的电活性磁激励，电磁振子。
By using broadband dielectric spectroscopy in the radio frequency and microwave range, we studied the magnetoelectric dynamics in the multiferroic chiral antiferromagnet MnWO_{4}. Above the multiferroic phase transition at T_{N2}≈12.6 K we observe a critical slowing of the corresponding magnetoelectric fluctuations resembling the soft-mode behavior in canonical ferroelectrics. This electric-field-driven excitation carries much less spectral weight than ordinary phonon modes. Also, the critical slowing down of this mode scales with an exponent larger than 1, which is expected for magnetic second-order phase transition scenarios. Therefore, the investigated dynamics have to be interpreted as the softening of an electrically active magnetic excitation, an electromagnon.