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arXiv · 1708.04345

Terahertz frequency magnetoelectric effect in Ni doped CaBaCo$_4$O$_7$

Shukai Yu·C. Dhanasekhar·Venimadhav Adyam·Skylar Deckoff-Jones·Michael K. L. Man·Julien Madeo·E. Laine Wong·Takaaki Harada·Bala M. K. Mariserla·Keshav M. Dani·Diyar Talbayev
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Abstract

We present a study of terahertz frequency magnetoelectric effect in ferrimagnetic pyroelectric CaBaCo$_4$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 CaBaCo$_{4-x}$Ni$_x$O$_7$.

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Shukai Yu, C. Dhanasekhar, Venimadhav Adyam, Skylar Deckoff-Jones, Michael K. L. Man, Julien Madeo, E. Laine Wong, Takaaki Harada, Bala M. K. Mariserla, Keshav M. Dani, Diyar Talbayev. 2017-08-14. Terahertz frequency magnetoelectric effect in Ni doped CaBaCo$_4$O$_7$. https://doi.org/10.1103/physrevb.96.094421

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