Strain-induced tetragonal distortions and multiferroic properties in polycrystalline ${\mathrm{Sr}}_{1-x}\mathrm{B}{\mathrm{a}}_x\mathrm{Mn}{\mathrm{O}}_3$ ( $x=0.43-0.45$ ) perovskites

Journal Article · 17 May 2018 · Physical Review Materials

DOI: https://doi.org/10.1103/PhysRevMaterials.2.054408 · OSTI ID:1439880

Somaily, H. ^[1]; Kolesnik, S. ^[1]; Mais, J. ^[1]; Brown, D. ^[1]; Chapagain, K. ^[1]; Dabrowski, B. ^[1]; Chmaissem, O. ^[2]

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1. Northern Illinois Univ., DeKalb, IL (United States). Dept. of Physics
2. Northern Illinois Univ., DeKalb, IL (United States). Dept. of Physics; Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division

Here, we report a comprehensive structure-property phase diagram of unique single-ion type-1 multiferroic pseudocubic Sr_1-xBa_xMnO₃ perovskites. Employing a specially designed multi-step reduction-oxidation synthesis technique, we describe the successful synthesis of previously unknown Sr_1-xBa_xMnO₃ compositions in their polycrystalline form with a significantly extended Ba solubility limit that is only rivaled by a very limited number of crystals and thin films grown under non-equilibrium conditions. Understanding the multiferroic interplay with structure in Sr_1-xBa_xMnO₃ is of great importance as it opens the door wide to the development of newer materials from the parent (AA’)(BB’) O₃ system with enhanced properties. To this end, using a combination of time-of-flight neutron and synchrotron x-ray scattering techniques, we determined the exact structures and quantified the Mn and oxygen polar distortions above and below T_C and T_N. In its ferroelectric state, the system crystalizes in the noncentrosymmetric tetragonal P4mm space group which gives rise to a large electric dipole moment P_s, in the z-direction, of 18.4 and 29.5 µC/cm² for x = 0.43 and 0.45, respectively. The two independently driven ferroelectric and magnetic order parameters are single-handedly accommodated by the Mn sublattice leading to a novel strain-assisted multiferroic behavior in agreement with many theoretical predictions. Our neutron diffraction results demonstrate the large and tunable suppression of the ferroelectric order at the onset of AFM ordering and confirm the coexistence and strong coupling of the two ferroic orders below T_N. The refined magnetic moments confirm the strong covalent bonding between Mn and the oxygen anions which is necessary for stabilizing the ferroelectric phase.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1439880
• Alternate ID(s): OSTI ID: 1437518
• Journal Information: Physical Review Materials, Vol. 2, Issue 5; ISSN 2475-9953
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English