Substrate Clamping Effects on Irreversible Domain Wall Dynamics in Lead Zirconate Titanate Thin Films

Abstract

The role of long-range strain interactions on domain wall dynamics is explored through macroscopic and local measurements of nonlinear behavior in mechanically clamped and released polycrystalline lead zirconate-titanate (PZT) films. Released films show a dramatic change in the global dielectric nonlinearity and its frequency dependence as a function of mechanical clamping. Furthermore, we observe a transition from strong clustering of the nonlinear response for the clamped case to almost uniform nonlinearity for the released film. This behavior is ascribed to increased mobility of domain walls. These results suggest the dominant role of collective strain interactions mediated by the local and global mechanical boundary conditions on the domain wall dynamics. The work presented in this Letter demonstrates that measurements on clamped films may considerably underestimate the piezoelectric coefficients and coupling constants of released structures used in microelectromechanical systems, energy harvesting systems, and microrobots. Strain in epitaxial oxide films has become a universally recognized method for tuning materials properties [1][2][3], enabling novel couplings between magnetic, lattice, and strain behaviors [4][5][6], stabilizing new phases [7] or domain morphologies [8]. Systematic studies of a material's response to strain enable exploration of the fundamental mechanisms responsible for, e.g., the ferroelectric instability [9][10][11][12].While strain effects on intrinsic properties [9,12] and domain morphologies [13,14] are readily amenable to theoretical and experimental studies, their role on local and emergent properties [15] in disordered materials, including polycrystalline ferroelectric films and relaxors, remains virtually unexplored [16,17], Indeed, many of these materials exhibit unique physical properties including giant electromechanical coupling coefficients, broad dispersions of dielectric permittivity, etc. [18][19][20][21]. These phenomena are often associated with the presence of nanoscale textures of domains or nanoscale phase separation [22][23][24]. In all these materials, the dominant order parameter is either strain (ferroelastics) or is strongly coupled to strain (relaxors, morphotropic systems), suggesting the significant role of frustrated or random strain interactions [25][26][27]. Correspondingly, tuning mechanical boundary conditions can significantly affect emergent behaviors in disordered ferroics and provide insight into corresponding coupling mechanisms.Here, we aim to explore domain wall dynamics as reflected in ferroelectric nonlinearities in model PbZr 0:52 Ti 0:48 O 3 thin films. In polycrystalline lead zirconate-titanate (PZT) ceramics, domain wall motion may contribute more than 50% of the dielectric and piezoelectric properties at room temperature [23,28]. However, in thin films these extrinsic contributions to the piezoelectric response can be severely limited by several factors, including substrate clamping [29]. Recent spatially resolved studies of piezoelectri...

Processing of rf-sputtered lead zirconate titanate thin films on copper foil substrates

“…Use of a more compliant substrate (than Si, for example) may reduce substrate clamping and improve the effective piezoelectric properties [11,12]. Griggio et al recently directly demonstrated the negative effect of substrate clamping on domain mobility [13]. Copper foil is also a candidate for transducers with non-planar geometries.…”

Ferroelectric properties of Pb(Zr,Ti)O3 films under ion-beam induced strain

“…It has been suggested that the different mechanical state of PZT films modifies the density and motion of non-180 domain walls and the polarization switching behavior to accommodate the strain, leading to a significant change in their piezoelectric and dielectric properties. [6][7][8] The contribution of the extrinsic parameters to an increase in the dielectric permittivity and tunability under biaxial tensile stress has been observed in other typical ferroelectric materials, (Ba,Sr)TiO 3 (BST). 9,10 Previous reports have also shown that mechanical stresses in ferroelectric films can affect the fatigue and imprint behavior, which have plagued the application of ferroelectric materials by changing the stability and the dynamics of domains under an external electric field.…”

Local Probing of Ferroelectric and Ferroelastic Switching through Stress‐Mediated Piezoelectric Spectroscopy

“…[15,16] In fact, recent studies have illustrated the unexpectedly large role of clamping on the electromechanical response of PZT thin films, suggesting the presence of nontrivial, large length-scales for strain interactions present in such samples. [17] Similarly, evidence has also been provided of avalanche-like behavior of multiple domain walls due to cooperative interactions across these large length scales in disordered ferroelectric thin films. [18] These considerations suggest that the role of local strains on ferroelectric and ferroelastic properties is central to both the piezoelectric and ferroelectric phenomena themselves.…”