Strain gradient is a normal phenomenon around a heterostructural interface in ultrathin film, and it is important to determine its effect on magnetic interactions to understand interfacial coupling. In this work, ultrathin PrSrMnO (PSMO) films on different substrates are studied. For PSMO film under different in-plane strain conditions, the saturated magnetization and Curie temperature can be qualitatively explained by double-exchange interaction and the Jahn–Teller distortion. However, the difference in the saturated magnetization with zero field cooling and 5 T field cooling is proportional to the strain gradient. Strain-gradient-induced structural disorder is proposed to enhance phonon–electron antiferromagnetic interactions and the corresponding antiferromagnetic-to-ferromagnetic phase transition via a strong magnetic field during the field cooling process. A non-monotonous structural transition of the MnO octahedral rotation can enlarge the strain gradient in PSMO film on a SrTiO substrate. This work demonstrates the existence of the flexomagnetic effect in ultrathin manganite film, which should be applicable to other complex oxide systems.

中文翻译：

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超薄 Pr0.67Sr0.33MnO3 薄膜中的磁相互作用与应变梯度


应变梯度是超薄膜异质结构界面周围的正常现象，确定其对磁相互作用的影响对于理解界面耦合非常重要。在这项工作中，研究了不同基底上的超薄 PrSrMnO (PSMO) 薄膜。对于不同面内应变条件下的PSMO薄膜，饱和磁化强度和居里温度可以通过双交换相互作用和Jahn-Teller畸变来定性解释。然而，零场冷却和 5 T 场冷却的饱和磁化强度的差异与应变梯度成正比。提出应变梯度引起的结构紊乱，以在场冷却过程中通过强磁场增强声子-电子反铁磁相互作用以及相应的反铁磁到铁磁相变。 MnO 八面体旋转的非单调结构转变可以扩大 SrTiO 衬底上 PSMO 薄膜的应变梯度。这项工作证明了超薄锰氧化物薄膜中存在挠曲磁效应，这应该适用于其他复杂的氧化物体系。