Title: Intrinsic conductance of ferroelectric domain walls

Abstract: Ferroelectric domain walls hold great promise for innovative applications in ferroelectric devices. However, the underlying mechanisms behind the observed giant conductance of charged domain walls remain poorly understood. Using a first-principles approach that incorporates Boltzmann transport theory and the relaxation time approximation, we determine the carrier concentration, mobility, and conductivity of domain walls with head-to-head and tail-to-tail polarization orientations. Our systematic exploration reveals that the accumulation of carriers, particularly their concentration, plays a dominant role in the domain wall conductance mechanism. However, the observed conductance differences between head-to-head and tail-to-tail domain walls are primarily due to differences in carrier mobility. The width of the domain wall is a key factor determining the device scale. Our calculated domain wall width is significantly smaller than previously reported values. This method, not limited to a certain ferroelectric material, can be used for the optimization and application development of various domain wall materials and devices.