Influence of nonmagnetic Zn substitution on the lattice and magnetoelectric dynamical properties of the multiferroic material CuO
Influence of nonmagnetic Zn substitution on the lattice and magnetoelectric dynamical properties of the multiferroic material CuO
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DOI：
10.1103/physrevb.90.064405
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发表时间：
2014-08-07
影响因子：
3.7
通讯作者：
Lloyd-Hughes, J.
中科院分区：
文献类型：
--
作者：
Jones, S. P. P.;Wurz, N. C.;Lloyd-Hughes, J.
利用太赫兹时域光谱技术研究了反常铁电体Cu_（1-x）Zn_xO（x = 0，x = 0.05）中的动态磁电耦合.锌的替代被发现，降低反铁磁有序温度和扩大的多铁性相，在自旋稀释和减少在晶胞体积的双重影响下。通过拉曼和傅里叶变换光谱以及壳模型计算阐明了锌取代对晶格动力学的影响。明显的软化的A（u）声子，活跃沿着铁电极化的方向，发生在多铁性状态的Cu 1-x，ZnxO，并表明强的自旋-声子耦合。相称的反铁磁相也表现出自旋-声子耦合，证明了拉曼活性区折叠声学声子，和自旋稀释降低自旋-声子耦合系数。虽然声子和磁振子模式扩大和移动作为合金引起的障碍的结果，电磁振子是相对不敏感的锌取代，增加能量而不扩大。结果表明，即使在无序自旋系统中，电磁振子和动态磁电耦合也能保持。
Dynamic magnetoelectric coupling in the improper ferroelectric Cu1-x ZnxO (x = 0, x = 0.05) was investigated using terahertz time-domain spectroscopy to probe electromagnon and magnon modes. Zinc substitution was found to reduce the antiferromagnetic ordering temperature and widen the multiferroic phase, under the dual influences of spin dilution and a reduction in unit-cell volume. The impact of Zn substitution on lattice dynamics was elucidated by Raman and Fourier-transform spectroscopy, and shell-model calculations. Pronounced softenings of the A(u) phonons, active along the direction of ferroelectric polarization, occur in the multiferroic state of Cu1-x,ZnxO, and indicate strong spin-phonon coupling. The commensurate antiferromagnetic phase also exhibits spin-phonon coupling, as evidenced by a Raman-active zone-folded acoustic phonon, and spin dilution reduces the spin-phonon coupling coefficient. While the phonon and magnon modes broaden and shift as a result of alloy-induced disorder, the electromagnon is relatively insensitive to Zn substitution, increasing in energy without widening. The results demonstrate that electromagnons and dynamic magnetoelectric coupling can be maintained even in disordered spin systems.