Relation between the EPR linewidths and the exchange integrals in ACrO2 (A = Li, NaandK)

The temperature dependence of the peak-to-peak EPR linewidth (ΔH_p-p) of the ACrO₂ (A = Li, Na, K) compounds in the X-band is typical for the previously observed antiferromagnetic interactions. All three oxides show a single absorption line with a lorentzian shape. As expected the room temperature values of ΔH_p-p in the Q-band are very close to those obtained in the X-band. Using the Anderson-Weiss model for exchange-narrowed Lorentzian lines and the high-temperature limit values for ΔH_p-p 's of all three oxides it was possible to estimate the coefficient relating the exchange integrals between the adjacent Cr³⁺-ions in the cationic sublattice to the corresponding exchange fields and the coefficient relating the crystal-field parameters of Cr³⁺-ions to the second moments of the spectral lines.