We present a study of the terahertz-frequency magnetoelectric effect in ferrimagnetic pyroelectric ${\mathrm{CaBaCo}}_4{\mathrm{O}}_7$ and its Ni-doped variants. The terahertz absorption spectrum of these materials consists of spin excitations and low-frequency infrared-active phonons. We studied the magnetic-field-induced changes in the terahertz refractive index and absorption in magnetic fields up to 17 T. We find that the magnetic field modulates the strength of infrared-active optical phonons near 1.2 and 1.6 THz. We use the Lorentz model of the dielectric function to analyze the measured magnetic-field dependence of the refractive index and absorption. We propose that most of the magnetoelectric effect is contributed by the optical phonons near 1.6 THz and higher frequency resonances. Our experimental results can be used to construct and validate more detailed theoretical descriptions of magnetoelectricity in ${\mathrm{CaBaCo}}_{4-x}{\mathrm{Ni}}_x{\mathrm{O}}_7$.

中文翻译：

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掺镍CaBaCo4O7中的太赫兹频率磁电效应

我们对铁磁热释电中的太赫兹频率磁电效应进行了研究 ${\mathrm{碳酸钙}}_4{\mathrm{Ø}}_7$及其镍掺杂变体。这些材料的太赫兹吸收光谱由自旋激发和低频红外活性声子组成。我们研究了磁场引起的太赫兹折射率的变化以及在高达17 T的磁场中的吸收。我们发现磁场在1.2和1.6 THz附近调节红外活性光子的强度。我们使用介电函数的Lorentz模型来分析测得的磁场对折射率和吸收率的依赖性。我们提出，大多数磁电效应是由接近1.6 THz的光子和更高频率的共振引起的。我们的实验结果可用于构建和验证更详细的磁电理论描述。${\mathrm{碳酸钙}}_{4-X}{你}_X{\mathrm{Ø}}_7$。