Pressure Control of Nonferroelastic Ferroelectric Domains in ErMnO₃

Abstract

Mechanical pressure controls the structural, electric, and magnetic order in solid-state systems, allowing tailoring of their physical properties. A well-established example is ferroelastic ferroelectrics, where the coupling between pressure and the primary symmetry-breaking order parameter enables hysteretic switching of the strain state and ferroelectric domain engineering.Here, we study the pressure-driven response in a nonferroelastic ferroelectric, ErMnO 3 , where the classical stress−strain coupling is absent and the domain formation is governed by creation− annihilation processes of topological defects. By annealing ErMnO 3 polycrystals under variable pressures in the MPa regime, we transform nonferroelastic vortex-like domains into stripe-like domains. The width of the stripe-like domains is determined by the applied pressure as we confirm by three-dimensional phase field simulations, showing that pressure leads to oriented layer-like periodic domains. Our work demonstrates the possibility to utilize mechanical pressure for domain engineering in nonferroelastic ferroelectrics, providing a lever to control their dielectric and piezoelectric responses.

Mechanical manipulation for ordered topological defects

“…It has been demonstrated that the vortex domains can be unfolded into mono-chiral topological stripes through high-temperature straining, via the opposite motion of vortices and antivortices ( 38 ), which suggests that the strain/strain gradient is an effective means to manipulate the vortex cores. The latest research endeavors extend this concept to pressure-driven domain engineering, substantiating that applied pressure at high temperature can indeed regulate the frequency and orientation of the induced stripe-like domains ( 39 ). However, high-temperature straining is rather inaccessible and highly uncontrollable.…”

Magnetoelectric coupling at the domain level in polycrystalline hexagonal ErMnO3

“…45,46 While mechanical stress of comparable magnitude has been reported to effect the ferroelectric domain structure. 23 We note, that related thermal activation effects remain to be studied, which goes beyond the scope of this work. In addition, the magnetic field may interact with the magnetic moment of the domain walls, 21 further promoting the movement of vortex cores.…”

“…Since the domain structure in single crystals of h-ErMnO 3 was found to be independent of the applied magnetic field up to magnetic fields of 4 T at 2.8 K, 40 we suggest that the observed changes are a consequence of the polycrystalline nature of the sample. It is established that vortex cores in h-RMnO 3 interact with strain fields, and a strain-induced movement of the vortex cores was theoretically 41 and experimentally 23,42,43 demonstrated for temperatures around T c . In our case, given the observed coupling and the geometrically driven ferroelectricity, we propose that strain may arise from magnetostriction, facilitated by the clamping of the individual grains.…”

“…The spatial resolution of Rcos# (amplitude R and phase # of the piezoelectric response) allows to distinguish domains with an antiparallel orientation of the ferroelectric polarization, while the grain boundaries separating grains of different crystallographic orientations are displayed by dashed white lines as explained in detail elsewhere. [22][23][24][25] The PFM image reveals a pronounced contrast, corresponding to the characteristic ferroelectric domain structure of polycrystalline h-ErMnO 3 , featuring a mixture of vortex-and stripe-like domains that form at T c % 1420 K. 26,27 To explore the low-temperature response of our polycrystalline h-ErMnO 3 sample, we measure the macroscopic dielectric permittivity as a function of temperature over 2-250 K for a range of frequencies from 1 to 10 3 Hz. As displayed in Fig.…”