Direct Observation of the Spin Gap in NaV ₂O ₅ by Submillimeter Wave ESR

Lattice vibrations ofα′−NaV2O5Popova1, Sushkov2, Климин3 et al. 2002Phys. Rev. B215120View full textAdd to dashboardCite

“…[21,39], Raman modes near 65 and 132 cm −1 have been assigned to one-and two-magnon scattering processes, respectively. The frequency 64-70 cm −1 of the lowest-frequency sharp feature in FIR and Raman spectra below T c corresponds well to the size of the gap ∆ 0 = 8.13 meV= 65.6 cm −1 at k = 0 obtained from submillimeter ESR measurements [37]. The transitions between the singlet ground state and the excited triplet state are forbidden (∆S = 1).…”

“…in E c) demonstrate a more slow growth of intensity below T c and a saturation at lower temperatures. We could not measure reliably the intensity dependence of the very weak feature at about 133 cm −1 in E c polarization but it seems to grow in the slowest way among all the studied modes and to follow the same temperature dependence as the spin-gap mode observed in optical ESR measurements [37] (also shown in Fig. 8).…”

“…The transitions between the singlet ground state and the excited triplet state are forbidden (∆S = 1). The Dzyaloshinsky-Moria (DM) interaction with DM vector along the c-axis breaks the selection rule for ESR (and FIR) E c transitions in α ′ -NaV 2 O 5 [37,34]. Recently, it has been shown theoretically [34] that for α ′ -NaV 2 O 5 the DM interaction results in finite Raman cross-section for both one-and two-magnon scattering processes.…”

Dzyaloshinskii-Moriya interaction inNaV2O5:A microscopic study

“…In this context it is of interest that very recent Electron Spin Resonance (ESR) experiments 18,19 have detected a considerable anisotropy of the absorption intensity with respect to the magnetic field orientation, which has been attributed to the DM interaction. Apart from ESR, Raman scattering in the presence of a magnetic field is an alternative experiment for the observation of possible effects due to DM interactions.…”

Low-energy excitations and dynamic Dzyaloshinskii-Moriya interaction inα′−NaV2ORõõm1, Hüvonen2, Nagel3 et al. 2004Phys. Rev. B261150View full textAdd to dashboardCite

“…One curve is at 8meV and the other at 10meV at the center of the Brillouin zone. More exact spin gap value, 8.13 meV (65.5 cm −1 ), has been determined by the high field electron spin resonance 15,16 . Doubling of the lattice constants along a-and b-axes and quadrupling along c-axis create additional Raman and infrared active modes at the phase transition temperature.…”