Facile Control of Ferroelastic Domain Patterns in Multiferroic Thin Films by a Scanning Tip Bias

Abstract

BiFeO 3 , known as the "holy grail of all multiferroics", provides an appealing platform for exploration of multifield coupling physics and design of functional devices. Many fantastic properties of BiFeO 3 are regulated by its ferroelastic domain structure. However, a facile programable control on the ferroelastic domain structure in BiFeO 3 remains challenging and our understanding on the existing control strategies is also far from complete. This work reports a facile control of ferroelastic domain patterns in BiFeO 3 thin films under area scanning poling by exploiting the tip bias as the control parameter. Combining scanning probe microscopy experiments and simulations, we found that BiFeO 3 thin films with pristine 71°rhombohedral-phase stripe domains exhibit at least four switching pathways solely by controlling the scanning tip bias. As a result, one can readily write mesoscopic topological defects into the films without the necessity to change the tip motion. The correlation between conductance of the scanned region and the switching pathway is further investigated. Our results extend the current understanding on the domain switching kinetics and the coupled electronic transport properties in BiFeO 3 thin films. The facile voltage control of ferroelastic domains should facilitate the development of configurable electronic and spintronic devices.

Complete Selective Switching of Ferroelastic Domain Stripes in Multiferroic Thin Films by Tip Scanning

“…Such a built-in field is common in real films due to the asymmetric interface environments and manifests itself in the ferroelectric hysteresis loops. Note also that other factors including the tip bias, film thickness, as well as the bias-loading time affect the relative volume faction of the switched domains, [29,33] we will explore the influences of these factors on the domain switching of BFO thin films under scanning tip bias in a near future work.…”

“…This might further require suitable built-in field, film thickness and loading time (i.e., scanning speed) as shown by our phase field simulation. [33] In summary, combining theoretical simulations and experiments, we investigated the tip-scanning-induced domain switching of R-phase BFO thin films with two-variant 71°ferroelastic stripes under the combining effects of multiple controlling variables, including tip scanning motion, tip bias, and built-in field. Phase field simulation results show that the tip bias and the builtin field affect the relative volume fraction of the 109°and 180°switched domains in BFO thin films under single-point loading, meanwhile the tip scanning further breaks the symmetry of the nucleated domains and leads to different switched domain patterns after tip scanning.…”

“…In the literature, research has shown that ferroelastic switching and the ferroelastic domain structure of BFO thin films can be efficiently manipulated by scanning probe microscopy (SPM) tip. [22,[28][29][30][31][32][33][34] For example, Cruz et al found in BFO films on (001) SrTiO 3 (STO) that 180°switching was favorable at low tip bias, while 71°and 109°switching occurred at higher tip bias. [28] Balke et al utilized the lateral tip motion to break the symmetry of domain nucleation and growth under the rotationally invariant SPM tip field and achieved a deterministic control of ferroelastic switching in BFO thin films.…”

“…[31] Recently, Chen et al proposed a method for selectively controlling 71°and 180°switching paths in R-phase BFO thin films by combining out-of-plane electric field and in-plane trailing field, [32] meanwhile we reported a facile manipulation of four switching paths in R-phase BFO thin films by solely varying the scanning tip bias. [33] Despite of these progresses and the fact that R-phase BFO thin films can possibly develop up-to eight degenerate states of twovariant 71°ferroelastic domain stripes, complete selective control of all the possible switching paths between these states has not yet been achieved. So far, the reported deterministic switching of R-phase BFO thin films has been limited to four states.…”

“…So far, the reported deterministic switching of R-phase BFO thin films has been limited to four states. [29,32,33] At the same time, there has been limited analysis of the combining effects of multiple controlling variables (e.g., tip scanning motion, tip bias, and built-in field) on the evolution of ferroelastic domain stripes in R-phase BFO thin films during tip scanning. The existing literature works mainly revealed the tip-scanninginduced domain switching of BFO thin films under the effect of single controlling variable.…”