Manipulation and Relaxation of Domain-Wall Topologies in Uniaxial Triple-Well Ferroelectrics

Domain-wall nanoelectronics requires control not only over wall creation but also over the field-off evolution of written configurations. Here, crystallographic anisotropy is used to achieve reversible domain-wall programming in the uniaxial triple-well ferroelectric Sn 2 P 2 S 6 . Single-crystal orientation, macroscopic polarisation, electrostrain, and piezoelectric measurements identify a low- E·P s geometry in which bulk field-polarisation coupling is strongly reduced relative to a high- E·P s reference. In situ piezoresponse force microscopy reveals a reproducible wall displacement near a nominal tip bias of 50-100 V, while the topographic channels remain unchanged. Following 100 V writing, field-off recovery was tracked for 90 min in three regions representing (i) isolated domain, (ii) a domain near a larger neighbour, and (iii) domain bridged to the extended matrix . The normalised area trajectories were evaluated using three nested models: an ordinary exponential, a zero-offset Kohlrausch-Williams-Watts (KWW) function without and with a retained-fraction correction. The isolated case exhibits slow stretched recovery ( τ = 29.8 min, β = 0.83) without a resolved offset. The neighbouring and bridged cases require retained-fraction KWW descriptions and show faster compressed recovery, with τ = 13.2 and 16.9 min, β = 1.14 and 1.08, and operational retained fractions of 0.065 and 0.111, respectively. Thus, local domain topology governs the recovery rate, kinetic form, and residual written fraction. The study therefore provides a purely geometrical, material-modification-free approach to resolving low- E·P s and high- E·P s states for domain-wall dynamics in non-oxide uniaxial ferroelectrics, while a triad of kinetic models is proposed to examine DW field-off relaxation processes.