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arXiv · 1101.3679

Theory of magnetoelectric resonance in two-dimensional $S=3/2$ antiferromagnet ${\rm Ba_2CoGe_2O_7}$ via spin-dependent metal-ligand hybridization mechanism

Shin Miyahara·Nobuo Furukawa
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Abstract

We investigate magnetic excitations in an $S=3/2$ Heisenberg model representing two-dimensional antiferromagnet ${\rm Ba_2CoGe_2O_7}$. In terahertz absorption experiment of the compound, Goldstone mode as well as novel magnetic excitations, conventional magnetic resonance at 2 meV and both electric- and magnetic-active excitation at 4 meV, have been observed. By introducing a hard uniaxial anisotropy term $Λ(S^z)^2$, three modes can be explained naturally. We also indicate that, via the spin-dependent metal-ligand hybridization mechanism, the 4 meV excitation is an electric-active mode through the coupling between spin and electric-dipole. Moreover, at 4 meV excitation, an interference between magnetic and electric responses emerges as a cross correlated effect. Such cross correlation effects explain the non-reciprocal linear directional dichroism observed in ${\rm Ba_2CoGe_2O_7}$.

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Shin Miyahara, Nobuo Furukawa. 2011-01-19. Theory of magnetoelectric resonance in two-dimensional $S=3/2$ antiferromagnet ${\rm Ba_2CoGe_2O_7}$ via spin-dependent metal-ligand hybridization mechanism. https://doi.org/10.1143/jpsj.80.073708

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