Defect‐Induced, Ferroelectric‐Like Switching and Adjustable Dielectric Tunability in Antiferroelectrics

• Published in: Advanced materials (Weinheim) 2023-06, Vol.35 (24), p.e2300257-n/a
• Main Authors: Pan, Hao, Tian, Zishen, Acharya, Megha, Huang, Xiaoxi, Kavle, Pravin, Zhang, Hongrui, Wu, Liyan, Chen, Dongfang, Carroll, John, Scales, Robert, Meyers, Cedric J. G., Coleman, Kathleen, Hanrahan, Brendan, Spanier, Jonathan E., Martin, Lane W.
• Format: Article
• Language: English
• Subjects: antiferroelectric materials; Antiferroelectricity; defects; dielectric tunability; Dielectrics; Ferroelectric materials; Kinetic energy; Materials science; Orthorhombic phase; Phase transitions; Point defects; Polarization; polarization switching; Switching; Temperature dependence; thin films
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202300257

Antiferroelectrics, which undergo a field‐induced phase transition to ferroelectric order that manifests as double‐hysteresis polarization switching, exhibit great potential for dielectric, electromechanical, and electrothermal applications. Compared to their ferroelectric cousins, however, considerably fewer efforts have been made to understand and control antiferroelectrics. Here, it is demonstrated that the polarization switching behavior of an antiferroelectric can be strongly influenced and effectively regulated by point defects. In films of the canonical antiferroelectric PbZrO3, decreasing oxygen pressure during deposition (and thus increasing adatom kinetic energy) causes unexpected “ferroelectric‐like” polarization switching although the films remain in the expected antiferroelectric orthorhombic phase. This “ferroelectric‐like” switching is correlated with the creation of bombardment‐induced point‐defect complexes which pin the antiferroelectric–ferroelectric phase boundaries, and thus effectively delay the phase transition under changing field. The effective pinning energy is extracted via temperature‐dependent switching‐kinetics studies. In turn, by controlling the concentration of defect complexes, the dielectric tunability of the PbZrO3 can be adjusted, including being able to convert between “positive” and “negative” tunability near zero field. This work reveals the important role and strong capability of defects to engineer antiferroelectrics for new performance and functionalities. In films of the canonical antiferroelectric PbZrO3, decreasing oxygen pressure during film deposition causes “ferroelectric‐like” polarization switching (although the films retain the antiferroelectric orthorhombic phase). This is correlated with low‐pressure bombardment‐induced point‐defect complexes that pin the antiferroelectric–ferroelectric phase‐transition boundaries. In turn, by controlling the concentration of defect complexes, the dielectric tunability of PbZrO3 can be adjusted.