Bernal-Salamanca Mónica, Herrero-Martín Javier, Konstantinović Zorica, Balcells Lluis, Pomar Alberto, Martínez Benjamín, Frontera Carlos
Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus UAB, 08193 Cerdanyola del Vallès, Spain.
ALBA Synchrotron Light Source, 08920 Cerdanyola del Vallès, Spain.
Nanomaterials (Basel). 2022 Dec 6;12(23):4337. doi: 10.3390/nano12234337.
In this work, we report a systematic study of the influence of film thickness on the structural and magnetic properties of epitaxial thin films of PrNiMnO (PNMO) double perovskite grown on top of two different (001)-SrTiO and (001)-LaAlO substrates by RF magnetron sputtering. A strong dependence of the structural and magnetic properties on the film thickness is found. The ferromagnetic transition temperature () and saturation magnetization (s) are found to decrease when reducing the film thickness. In our case, the thinnest films show a loss of ferromagnetism at the film-substrate interface. In addition, the electronic structure of some characteristic PNMO samples is deeply analyzed using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements and compared with theoretical simulations. Our results show that the oxidation states of Ni and Mn ions are stabilized as Ni and Mn, thus the ferromagnetism is mainly due to Ni-O-Mn superexchange interactions, even in samples with poor ferromagnetic properties. XMCD results also make evident large variations on the spin and orbital contributions to the magnetic moment as the film's thickness decreases.
在这项工作中，我们报告了一项关于薄膜厚度对通过射频磁控溅射生长在两种不同的（001）-SrTiO和（001）-LaAlO衬底上的PrNiMnO（PNMO）双钙钛矿外延薄膜的结构和磁性影响的系统研究。发现结构和磁性对薄膜厚度有强烈依赖性。当减小薄膜厚度时，铁磁转变温度（）和饱和磁化强度（s）会降低。在我们的研究中，最薄的薄膜在薄膜-衬底界面处表现出铁磁性的丧失。此外，使用X射线吸收光谱（XAS）和X射线磁圆二色性（XMCD）测量对一些典型PNMO样品的电子结构进行了深入分析，并与理论模拟进行了比较。我们的结果表明，Ni和Mn离子的氧化态稳定为Ni和Mn，因此即使在铁磁性能较差的样品中，铁磁性主要归因于Ni-O-Mn超交换相互作用。XMCD结果还表明，随着薄膜厚度的减小，自旋和轨道对磁矩的贡献有很大变化。
