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, and Diyar Talbayev
https://journals.aps.org/prb/accepted/72074O5dR991bd3a430230a86e2aeb528788ab341
We present a study of terahertz frequency magnetoelectric effect in ferrimagnetic pyroelectric \cbco 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 CaBaCo4-xNixO7.
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