Dey Urmimala, Senn Mark S, Bristowe Nicholas C
Centre for Materials Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom.
Department of Chemistry, University of Warwick, Gibbet Hill, Coventry CV4 7AL, United Kingdom.
J Phys Condens Matter. 2023 Nov 23;36(9). doi: 10.1088/1361-648X/ad0d27.
Type-II multiferroics, in which the magnetic order breaks inversion symmetry, are appealing for both fundamental and applied research due their intrinsic coupling between magnetic and electrical orders. Using first-principles calculations we study the ground state magnetic behaviour of BaMnOwhich has been classified as a type-II multiferroic in recent experiments. Our constrained moment calculations with the proposed experimental magnetic structure shows the spontaneous emergence of a polar mode giving rise to an electrical polarisation comparable to other known type-II multiferroics. When the constraints on the magnetic moments are removed, the spins self-consistently relax into a canted antiferromagnetic ground state configuration where two magnetic modes transforming as distinct irreducible representations coexist. While the dominant magnetic mode matches well with the previous experimental observations, the second mode is found to possess a different character resulting in a non-polar ground state. Interestingly, the non-polar magnetic ground state exhibits a significantly strong linear magnetoelectric (ME) coupling comparable to the well-known multiferroic BiFeO, suggesting strategies to design new linear MEs.
II型多铁性材料中，磁有序破坏了空间反演对称性，由于其磁序和电序之间的固有耦合，在基础研究和应用研究方面都颇具吸引力。我们利用第一性原理计算研究了BaMnO的基态磁行为，该材料在最近的实验中被归类为II型多铁性材料。我们对所提出的实验磁结构进行的受限矩计算表明，自发出现了一种极化模式，产生的电极化与其他已知的II型多铁性材料相当。当去除对磁矩的约束时，自旋自洽地弛豫到一个倾斜反铁磁基态构型，其中两个作为不同不可约表示变换的磁模式共存。虽然主导磁模式与先前的实验观测结果很好地匹配，但发现第二个模式具有不同的特征，导致非极性基态。有趣的是，非极性磁基态表现出与著名的多铁性材料BiFeO相当的显著强线性磁电（ME）耦合，这为设计新型线性磁电材料提供了策略。
