Intrinsic Conductance of Ferroelectric Charged Domain Walls

• Published in: Physics (Online) Vol. 6; no. 3; pp. 1083 - 1097
• Main Author: Yang, Feng
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2024
• Subjects: Approximation; Carrier density; Carrier mobility; charged domain wall; Compressive properties; conductance; Current carriers; Domain walls; Electric fields; Electrons; Ferroelectric materials; Ferroelectricity; ferroelectrics; First principles; Periodic structures; Point defects; Relaxation time; Semiconductors; Thin films; Transport theory
• ISSN: 2624-8174; 2624-8174
• DOI: 10.3390/physics6030067

Ferroelectric charged domain walls offer a revolutionary path for next-generation ferroelectric devices due to their exceptional conductivity within an otherwise insulating matrix. However, quantitative understanding of this “giant conductivity” has remained elusive due to the lack of robust models describing carrier behavior within CDWs. The current paper bridges this critical knowledge gap by employing a first-principles approach that incorporates Boltzmann transport theory and the relaxation time approximation. This strategy enables the calculation of carrier concentration, mobility, and conductivity for both head-to-head and tail-to-tail domain wall configurations within a stabilized periodic structure. The comprehensive transport analysis given here reveals that the accumulation of charge carriers, particularly their concentration, is the dominant factor governing domain wall conductance. Interestingly, observed conductance differences between head-to-head and tail-to-tail walls primarily arise from variations in carrier mobility. Additionally, this study demonstrates a significantly reduced domain wall width compared to previous reports. This miniaturization is attributed to the presence of compressive strain, which lowers the energy barrier for electron–hole pair generation. Furthermore, the findings here suggest that reducing the band gap presents a viable strategy for stabilizing charged domain walls. These results pave the way for the optimization and development of domain wall devices across a spectrum of ferroelectric materials.