Flexoelectric healing of intrinsically more conductive nanochannels in NdNiO3 thin films

• Published in: Applied surface science 2019-12, Vol.497, p.143727, Article 143727
• Main Authors: Seol, Daehee, Kim, Sungho, Oh, Chadol, Heo, Seung-Yang, Jang, Woo-Sung, Jeong, Hu Young, Kim, Young-Min, Son, Junwoo, Kim, Yunseok
• Format: Article
• Language: English
• Subjects: Atomic force microscopy; Flexoelectric healing; Metal-insulator transition; NdNiO3 thin films; Rare-earth nickelates
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2019.143727

Rare-earth nickelates have received great attention owing to the extreme sensitivity of their metal-insulator transition (MIT) and particularly the local defect state under external perturbation. Accordingly, it is critical to effectively control their local defect state to tailor the MIT. However, although macroscopic MIT behavior has been extensively studied, the relationship between the local defect state related to polar discontinuity and MIT has been rarely investigated. Herein, we demonstrate the presence of intrinsic conductive nanochannels due to the Ni deficiency induced by the polar discontinuity and the flexoelectric healing of such nanochannels in NdNiO3 thin films using atomic force microscopy (AFM). The results indicate that the intrinsic conductive nanochannels are likely related to the Ni vacancy. Intriguingly, these conductive nanochannels are effectively removed by the application of mechanical force with the AFM tip, i.e., flexoelectric healing. Our findings suggest that mechanical stimuli can be one of the effective ways for modulating the intrinsic defect state and the corresponding properties at the nanoscale. •A epitaxial NdNiO3 (NNO) thin films was grown on (001)-oriented SrTiO3 substrate by pulsed laser deposition.•The presence of intrinsic conductive nanochannels owing to Ni deficiency was observed in NNO thin films.•The conductive nanochannels are effectively removed by the application of mechanical force, i.e., flexoelectric healing.