Submillimeter Wave ESR Study of Spin Gap Excitations in CuGeO3

Abstract

Transitions between the ground singlet state to the excited triplet state has been observed in CuGeO3 by means of submillimeter wave electron spin resonance. The strong absorption intensity shows the break down of the selection rule. The energy gap at zero field is evaluated to be 570 GHz(2.36 meV) and this value is nearly identical to the gap at the zone center observed by inelastic neutron scattering. The absorption intensity shows strong field orientation dependence but shows no significant dependence on magnetic field intensity. These features have been explained by considering the existence of Dzyaloshinsky-Moriya (DM) antisymmetric exchange interaction. The doping effect on this singlet-triplet excitation has been also studied. A drastic broadening of the absorption line is observed by the doping of only 0.5 % of Si.

arXiv comment6 pages, 8figures submitted to J. Phys. Soc. Jpn

References in corpus (3)

• Double gap and solitonic excitations in the spin-Peierls chain CuGeO3
• Dynamics in the dimerised and high field incommensurate phase of CuGeO${}_3$
• Temperature Dependence of the Spin-Peierls Energy Gap and Anomalous Line Shapes in CuGeO${}_3$

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• High frequency ESR investigation on dynamical charge disproportionation and spin gap excitation in NaV_2O_5
• Anomalous Spin Dynamics observed by High Frequency ESR in Honeycomb Lattice Antiferromagnet InCu2/3V1/3O3
• Theory of phonon-assisted "forbidden" optical transitions in spin-gapped systems
• Field-induced structural evolution in the spin-Peierls compound CuGeO${}_3$: high-field ESR study
• Optical spectroscopy of pure and doped CuGeO3