Hyperfine local probe study of alkaline-earth manganites SrMnO3 and BaMnO3

TL;DR

This study uses perturbed angular correlation measurements and first-principles calculations to analyze the electric field gradients in alkaline-earth manganites, revealing site assignments and predicting hyperfine parameters in related multiferroic compounds.

Contribution

It provides the first combined experimental and theoretical analysis of EFGs in SrMnO3 and BaMnO3 manganites, including site identification and hyperfine parameter predictions for a multiferroic variant.

Findings

EFG remains approximately constant over a wide temperature range.

Site assignments for probes are made based on experimental and theoretical data.

Hyperfine parameters are predicted for Sr0.5Ba0.5MnO3, showing minimal variation with structure and polarization.

Abstract

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 Sr0.5Ba0.5MnO3 , and its variation with the structure and electric polarization, which is found to be very small.