Abstract
Magnetic excitations in the multiferroic Ba2CoGe2O7 are measured by combination of unpolarized and polarized neutron-scattering techniques. The unpolarized neutron spectrum reveals an anisotropic Q dependence of the intensity of the electromagnon mode at 4 meV. The analysis of the polarized neutron spectra identifies the directions of the magnetic fluctuations of the observed modes. The determined modes are consistent with the calculation by the extended spin-wave theory. A couple of transverse modes and a single longitudinal mode are involved in the magnetic excitation of Ba2CoGe2O7. The longitudinal fluctuation takes on a main role in the electromagnon mode.
Original language | English |
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Article number | 214437 |
Journal | Physical Review B |
Volume | 97 |
Issue number | 21 |
DOIs | |
State | Published - Jun 29 2018 |
Funding
The unpolarized neutron experiment was performed by using HYSPEC at SNS/ORNL, USA. The research at ORNL's Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. The polarized neutron experiment was performed by using TASP at SINQ/PSI, Switzerland. Travel expense for the neutron experiment on HYSPEC was supported by the U.S.-Japan collaboration program, and that on TASP was supported by the General User Program for Neutron Scattering Experiments, Institute for Solid State Physics, The University of Tokyo (Proposals No. 13570 and No. 15518). This paper was supported by KAKENHI (Grants No. 15K05123 and No. 17K05516) from the Ministry of Education, Culture, Sports, Science and Technology, Japan.