Abstract-Terahertz frequency magnetoelectric effect in Ni doped CaBaCo4O7

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

(Submitted on 14 Aug 2017)

https://arxiv.org/abs/1708.04345

We present a study of terahertz frequency magnetoelectric effect in ferrimagnetic pyroelectric CaBaCo4O7 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.