Direct Observation of Hot Spots in Ferroelectric Domain Wall Devices by Scanning Thermal Microscopy

Abstract: Ferroelectric domain wall devices offer a promising route to low voltage, reconfigurable nanoelectronics by confining currents to nanoscale conducting interfaces within an insulating bulk. However, resistive heating due to domain wall conduction still remains unexplored. Here, we employ scanning thermal microscopy to directly image hot spots in thin-film lithium niobate domain wall devices. Piezoresponse force microscopy shows that the hot spots correlate with nanodomain structure and thermal mapping reveals surface temperature rises of up to ~ 20 K, levels that are unlikely to negatively affect device performance. This is due to the moderate conductivity of domain walls, their voltage-tunable erasure, and distributed current pathways, which inherently limit power dissipation and peak temperatures. Finite element electrothermal modelling indicates that domain walls behave as pseudo-planar heat sources, distinct from filament-based models. These findings highlight the potential for domain wall devices as an energy-efficient, thermally stable platform for emerging memory and logic applications.