Current-induced nonuniform enhancement of sheet resistance in Ar+ -irradiated SrTiO3

Abstract

The sheet resistance Rs of Ar + irradiated SrTiO3 in patterns with a length scale of several microns increases significantly below ~40 K in connection with driving currents exceeding a certain threshold. The initial lower Rs is recovered upon warming with accelerated recovery around 70 and 160 K. Scanning SQUID microscopy shows local irreversible changes in the spatial distribution of the current with a length scale of several microns. We attribute the observed non-uniform enhancement of Rs to the attraction of the charged single-and di-oxygen vacancies by the crystallographic domain boundaries in SrTiO3. The boundaries which are nearly ferroelectric below 40 K are polarized by the local electrical field associated with the driven current and the clustered vacancies which suppress conductivity in their vicinity yield a noticeable enhancement in the device resistance when the current path width is on the order of the boundary extension. The temperatures of accelerated conductivity recovery are associated with the energy barriers for the diffusion of the two types of vacancies.2

Bimodal Phase Diagram of the Superfluid Density in LaAlO3/SrTiO3 Revealed by an Interfacial Waveguide Resonator

“…Below T 105 K, STO undergoes a structural transition from a cubic to a tetragonal phase [41,42]. Current maps of charge flow in LAO/STO reveals a filamentary structure of the pattern which is related to the striped electrostatic potential modulation arising from the tetragonal domains in STO at low temperature [43][44][45][46][47].…”

Strain-induced conductivity accelerated recoveries in LaAlO3/SrTiO3 heterostructure with millimeter scale

“…Similar anomalies have also been observed in the patterned LAO/STO and STO samples with the length scale of several μm. 28,32,33 The anomalies presenting in these references significantly enhance when the sample length decreases to nm scale, the previous works considered that the anomalies could only occur in several u.c. layers LAO/STO samples with length scale of micron.…”

“…Roy and Klein et al also found the current-induced nonuniform enhancement of sheet resistance due to the interaction between domain walls and oxygen vacancies in STO. 28 Erlich et al 30 confirmed the channel behavior of conductivity by using the polarized light microscopy technology. Ma et al 31 carried out SEM imaging at low temperature and found that the ferroelectric can be induced within the twin walls in STO beyond the critical electrical field.…”

“… 27 The structure transition of STO leads the abundant structure domain on STO surface. 28–31 Kalisky and Moler et al 29 used superconducting quantum interference device (SQUID) to measure the localized magnetic field, and found the domain structure strongly modified the local conductivity, which showed as the current intensity increases along the domain walls. Roy and Klein et al also found the current-induced nonuniform enhancement of sheet resistance due to the interaction between domain walls and oxygen vacancies in STO.…”

Unveiling Temperature-Induced Structural Domains and Movement of Oxygen Vacancies in SrTiO3 with Graphene

“… 8 − 10 Further, oxygen vacancies tend to accumulate at STO domain walls and act as channels for the movement of oxygen vacancies that can dramatically influence the dielectric environment both with temperature and with electric fields. 11 , 12 This intricate interplay between structural transition and electronic transport has been studied by several groups using different macroscopic and transport probes involving different levels of complexity. The domain walls were found to host interesting properties, such as field-induced ferroelectricity, high mobilities up to low temperature, and enhanced conductivity.…”