Vertical Strain-Driven Antiferromagnetic to Ferromagnetic Phase Transition in EuTiO₃ Nanocomposite Thin Films
2020
Lin, Yisong | Choi, Eun-mi | Lu, Ping | Sun, Xing | Wu, Rui | Yun, Chao | Zhu, Bonan | Wang, Haiyan | Li, Weiwei | Maity, Tuhin | MacManus-Driscoll, Judith
Three-dimensional (3D) strain induced in self-assembled vertically aligned nanocomposite (VAN) epitaxial films provides an unrivaled method to induce very large strains in thin films. Here, by growing VAN films of EuTiO₃ (ETO)–Eu₂O₃ (EO) with different EO fractions, the vertical strain was systematically increased in ETO, up to 3.15%, and the Eu–Ti–Eu bond angle along ⟨111⟩ decreased by up to 1°, leading to a weakening of the antiferromagnetic interactions and switching from antiferromagnetic to ferromagnetic behavior. Our work has shown for the first time that Eu–Ti–Eu superexchange interactions play a key role in determining the magnetic ground state of ETO. More broadly, our work serves as an exemplar to show that multifunctionalities in strong spin–lattice coupling perovskite oxides can be uniquely tuned at the atomic scale using simple VAN structures.
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