[en] The Perturbed Angular Correlation (PAC) technique was applied to study the yttrium local environment in YMnO₃ multiferroic manganite. The electric field gradients (EFG) at the Y site have been measured as function of temperature, covering both ferroelectric and magnetic transitions. The results were compared with point charge model (PCM) calculations. The experimental results show two different EFG distributions for all temperatures. Only one can be directly attributed to the yttrium crystalline site in the hexagonal structure.

[en] We report perturbed angular correlation measurements with ^111mCd/¹¹¹Cd and ¹¹¹In/¹¹¹Cd probes, at the ISOLDE-CERN facility, in the manganite compounds BaMnO₃, with the 6H and 15R polymorphs, and SrMnO₃, with the 4H polymorph. The electric field gradient (EFG) is measured, and found approximately constant in a large temperature range for all the compounds. The EFG is also calculated from first principles with density functional theory, and compared with experimental results by considering diluted substitutional Cd impurities. Based on the results, we assign as sites for the probes the Ba (for BaMnO₃-6H, 15R) and Sr (for SrMnO₃-4H) sites, apart from fractions of undetermined origin in the case of BaMnO₃-6H. We predict the hyperfine parameters in the recently synthesized multiferroic manganite Sr_0.5Ba_0.5MnO₃, and its variation with the structure and electric polarization, which is found to be very small. (paper)