# Direct Thermal Imaging of Domain Wall Hot Spots in LiNbO3

## TL;DR

This paper uses thermal imaging to study heat generation in domain walls of lithium niobate, showing they can operate efficiently without significant overheating.

## Contribution

The study directly visualizes and quantifies thermal hot spots in domain wall devices using scanning thermal microscopy.

## Key findings

- Thermal hot spots in domain walls show temperature rises of up to ≈20 K.
- Domain walls exhibit moderate conductivity and distributed current pathways, limiting power dissipation.
- Finite element modeling reveals domain walls act as pseudo-planar heat sources.

## 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, the potential for resistive heating and unregulated temperature increases due to domain wall conduction remains unexplored. Here, scanning thermal microscopy is employed 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 ≈20 K at most, levels that are unlikely to negatively affect device performance. This is due to the moderate electrical 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 the filament‐based heating typically observed in resistive switching oxides. These findings highlight the potential for domain wall devices as an energy‐efficient, thermally stable platform for emerging memory and logic applications.

Ferroelectric domain walls are conducting interfaces that are fully reconfigurable by electrical signals, leading to conceptually new types of multi‐state memory devices. However, detrimental self‐heating of the devices due to highly confined power dissipation in domain walls can occur. Here, Scanning Thermal Microscopy is used to directly visualize hot spots associated with polar nanodomain structure, with temperatures up to ≈20 K observed.