Mar 20 – 23, 2023
Campus Garching
Europe/Berlin timezone

Magnetism and dynamics in multiferroic antiferromagnet Ba2CoGe2O7

Mar 20, 2023, 3:40 PM
MW 0 001 - Lecture hall (Fakultät für Maschinenwesen)

MW 0 001 - Lecture hall

Fakultät für Maschinenwesen

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Talk (17 + 3 min) Chemistry of Materials (Structure and Spectroscopy) Magnetic Structures


Dr Rajesh Dutta (Institut für Kristallographie, RWTH Aachen University)


Multiferroic Ba$_2$CoGe$_2$O$_7$ is well known for having an unconventional metal-ligand d-p hybridization mechanism responsible for the magnetically induced ferroelectricity [1,2]. It exhibits many exotic quantum phenomena, and among them anisotropic spin excitations and self-tunable single ion anisotropy under external applied magnetic field have been observed recently, using inelastic neutron scattering (INS) technique [3]. A spin gap of about 0.1 meV has been observed under zero magnetic field and interpreted as an effect of spin-nematic interaction [4]. However, we have predicted such gap via linear spin wave theory by introducing the Dzyaloshinskii–Moriya interaction in the spin Hamiltonian. We have observed a spin gap of 0.105 meV in energy at 2 K under zero magnetic field and the gap energy decreases with increasing temperature. We enlighten the discussion on understanding the origin of the zero-field spin gap in details.

[1] H. Murakawa, et al., “Comprehensive study of the ferroelectricity induced by the spindependent d-p hybridization mechanism in Ba$_2$XGe$_2$O$_7$ (X = Mn, Co, and Cu),” Phys. Rev. B 85, 174106, 2012.
[2] H. Murakawa, et al., “Ferroelectricity induced by spin-dependent metal-ligand hybridization in Ba$_2$CoGe$_2$O$_7$,” Phys. Rev. Lett. 105, 137202, 2010.

[3] R. Dutta, et al., “Spin dynamics study and experimental realization of tunable single-ion anisotropy in multiferroic Ba$_2$CoGe$_2$O$_7$ under external magnetic fields,” Phys. Rev. B, 104, L020403, 2021.

[4] M. Soda, et al., “Spin-nematic interaction in the multiferroic compound Ba$_2$CoGe$_2$O$_7$,” Phys. Rev. Lett., 112, 127205, 2014.

Primary author

Dr Rajesh Dutta (Institut für Kristallographie, RWTH Aachen University)


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