2009/06/19 by Ch. Kant, J. Deisenhofer, T. Rudolf +9 · 2 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Multiferroics and related materials #Physics of Superconductivity and Magnetism #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.80.214417
published as Phys. Rev. B 80, 214417 (2009) · 11 pages, 13 figures
arxiv created 2009/06/19 · openalex publication_date 2009/12/17 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
We report on infrared, Raman, magnetic susceptibility, and specific-heat measurements on CdCr2O4 and ZnCr2O4 single crystals. We estimate the nearest-neighbor and next-nearest-neighbor exchange constants from the magnetic susceptibility and extract the spin-spin correlation functions obtained from the magnetic susceptibility and the magnetic contribution to the specific heat. By comparing with the frequency shift of the infrared optical phonons above TN, we derive estimates for the spin-phonon coupling constants in these systems. The observation of phonon modes which are both Raman and infrared active suggest the loss of inversion symmetry below the N'eel temperature in CdCr2O4 in agreement with theoretical predictions by Chern et al. [Phys. Rev. B 74, 060405(R) (2006)]. In ZnCr2O4 several new modes appear below TN but no phonon modes could be detected which are both Raman and infrared active.