Twisted Integration of Complex Oxide Magnetoelectric Heterostructures via Water-Etching and Transfer Process

Guannan Yang; Guohua Dong; Butong Zhang; Xu Xu; Yanan Zhao; Zhongqiang Hu; Ming Liu

doi:10.1007/s40820-023-01233-z

Twisted Integration of Complex Oxide Magnetoelectric Heterostructures via Water-Etching and Transfer Process

Nanomicro Lett. 2023 Nov 17;16(1):19. doi: 10.1007/s40820-023-01233-z.

Authors

Guannan Yang¹, Guohua Dong², Butong Zhang¹, Xu Xu¹, Yanan Zhao¹, Zhongqiang Hu³, Ming Liu¹

Affiliations

¹ State Key Laboratory for Manufacturing Systems Engineering, Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Engineering Research Center of Spin Quantum Sensor Chips, Universities of Shaanxi Province, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China.
² State Key Laboratory for Manufacturing Systems Engineering, Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Engineering Research Center of Spin Quantum Sensor Chips, Universities of Shaanxi Province, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China. guohuadong@xjtu.edu.cn.
³ State Key Laboratory for Manufacturing Systems Engineering, Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Engineering Research Center of Spin Quantum Sensor Chips, Universities of Shaanxi Province, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China. zhongqianghu@xjtu.edu.cn.

Abstract

The (001)-oriented ferromagnetic La_0.67Sr_0.33MnO₃ films are stuck onto the (011)-oriented ferroelectric single-crystal 0.7Pb(Mg_1/3Nb_2/3)O₃-0.3PbTiO₃ substrate with 0° and 45° twist angle. By applying a 7.2 kV cm^-1 electric field, the coexistence of uniaxial and fourfold in-plane magnetic anisotropy is observed in 45° Sample, while a typical uniaxial anisotropy is found in 0° Sample. Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain engineering. In recent years, lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal orientations. Moreover, twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures. A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process, which could provide some insight in to the physical phenomena. In this work, the La_0.67Sr_0.33MnO₃ (001)/0.7Pb(Mg_1/3Nb_2/3)O₃-0.3PbTiO₃ (011) (LSMO/PMN-PT) heterostructures with 45º and 0º twist angles were assembled via water-etching and transfer process. The transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO < 110 >. A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO [110] easy axis is observed for the 45° Sample by applying a 7.2 kV cm^-1 electrical field, significantly different from a uniaxial anisotropy with LSMO [100] easy axis for the 0° Sample. The fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45° twist angle causes different lattice distortion of LSMO, thereby enhancing both the fourfold and uniaxial anisotropy. This work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.

Keywords: Epitaxial lift-off; Ferromagnetic resonance; Magnetic anisotropy; Magnetoelectric heterostructures; Twist angle.