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Raman Scattering from Magnetic Excitations in the Spin Ladder Compounds CaV2O5 and MgV2O5

M. J. Konstantinovic·Z. V. Popovic·M. Isobe·Y. Ueda
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Abstract

We present the Raman-scattering spectra of CaV2O5 and MgV2O5. The magnetic contribution in the Raman spectra of CaV2O5 is found in the form of a strong asymmetric line, centered at 2Delta, with a tail on the high-energy side. Our analysis of its spectral shape shows that the magnetic ordering in CaV2O5 can be described using a S=1/2 two-leg ladder Heisenberg antiferromagnetic model with Jparallel/Jperp = 0.1, and a small interladder exchange. The spin gap and exchange constant are estimated to be Delta = 400 cm-1 (570 K) and Jperp = 640 K. No magnon bound states are found. In contrast to CaV2O5 the existence of the spin-gap is not confirmed in MgV2O5, since we found no feature in the spectra which could be associated with the onset of the two-magnon continuum. Instead, we observe two-magnon excitation at 340 cm-1, presumably related to the top of the two-magnon brunch.

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M. J. Konstantinovic, Z. V. Popovic, M. Isobe, Y. Ueda. 2000-06-13. Raman Scattering from Magnetic Excitations in the Spin Ladder Compounds CaV2O5 and MgV2O5. https://doi.org/10.1103/physrevb.61.15185

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