Golovina Iryna S, Lemishko Serhii V, Morozovska Anna N
Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, pr. Nauky 41, Kyiv, 03028, Ukraine.
Department of Materials Science and Engineering, Drexel University, Philadelphia, PA, 19104, USA.
Nanoscale Res Lett. 2017 Dec;12(1):382. doi: 10.1186/s11671-017-2146-1. Epub 2017 Jun 2.
Nanoparticles of potassium tantalate (KTaO) and potassium niobate (KNbO) were synthesized by oxidation of metallic tantalum in molten potassium nitrate with the addition of potassium hydroxide. Magnetization curves obtained on these ferroelectric nanoparticles exhibit a weak ferromagnetism, while these compounds are nonmagnetic in a bulk. The experimental data are used as a start point for theoretical calculations. We consider a microscopic mechanism that leads to the emerging of a ferromagnetic ordering in ferroelectric nanoparticles. Our approach is based on the percolation of magnetic polarons assuming the dominant role of the oxygen vacancies. It describes the formation of surface magnetic polarons, in which an exchange interaction between electrons trapped in oxygen vacancies is mediated by magnetic impurity Fe ions. The dependences of percolation radius on concentration of the oxygen vacancies and magnetic defects are determined in the framework of percolation theory.
通过在熔融硝酸钾中加入氢氧化钾氧化金属钽，合成了钽酸钾（KTaO）和铌酸钾（KNbO）纳米颗粒。在这些铁电纳米颗粒上获得的磁化曲线表现出弱铁磁性，而这些化合物在体相中是非磁性的。实验数据用作理论计算的起点。我们考虑了一种导致铁电纳米颗粒中出现铁磁有序的微观机制。我们的方法基于磁极化子的渗流，假设氧空位起主导作用。它描述了表面磁极化子的形成，其中捕获在氧空位中的电子之间的交换相互作用由磁性杂质Fe离子介导。在渗流理论框架内确定了渗流半径对氧空位浓度和磁缺陷的依赖性。
