Ultra-low coercive field of improper ferroelectric Ca3Ti2O7 epitaxial thin films

Abstract

This paper was selected as Featured ARTICLES YOU MAY BE INTERESTED IN Interrelation between domain structures and polarization switching in hybrid improper ferroelectric Ca 3 (Mn,Ti) 2 O 7

Hybrid Improper Ferroelectricity in (Sr,Ca)3Sn2O7 and Beyond: Universal Relationship between Ferroelectric Transition Temperature and Tolerance Factor in n = 2 Ruddlesden–Popper Phases

“…This form of ferroelectricity should be prevalent in perovskiterelated materials because the octahedral rotations/tilts are ubiquitous structural distortions 21 (which are primarily of geometric origin and are driven by the size mismatch of the constituent ions). Indeed, a number of layered perovskites have been proposed as potential hybrid improper ferroelectrics through the integrated approach of symmetry arguments and first-principles calculations [22][23][24][25][26][27][28][29][30] , some of which have been experimentally confirmed to exhibit switchable polarization [31][32][33][34][35][36][37][38] , or at least crystalize in polar structures [39][40][41][42][43][44][45][46] . One can now utilize group theory to elucidate symmetry breaking caused by given distortions and identify whether their combinations result in a polar symmetry, and then the ferroelectricity.…”

Polarization switching dynamics and switchable diode effect in hybrid improper ferroelectric Ca3Ti2O7 ceramics

“…In a report by Huang et al, the high‐energy antiphase boundaries and ferroelastic tilting and rotation domain walls were found to dominate the nucleation controlled kinetics of polarization flipping in a CTO single crystal . Very recently, employing pulsed laser deposition, Li et al deposited CTO thin films onto SrTiO 3 single‐crystal substrates and found that CTO film exhibits a coercive field of 5 kV/cm at a temperature of 2 K. While the coercive field of bulk CTO single crystal is around 120 kV/cm . The remnant polarization values of CTO have been reported to be 8, 0.6, and 8 μC/cm 2 for single crystal along the [100] direction, ceramic and thin film, respectively.…”

“…Very recently, employing pulsed laser deposition, Li et al deposited CTO thin films onto SrTiO 3 single‐crystal substrates and found that CTO film exhibits a coercive field of 5 kV/cm at a temperature of 2 K. While the coercive field of bulk CTO single crystal is around 120 kV/cm . The remnant polarization values of CTO have been reported to be 8, 0.6, and 8 μC/cm 2 for single crystal along the [100] direction, ceramic and thin film, respectively. Furthermore, those polarization characteristics were all probed and extracted from the so‐called positive‐up‐negative‐down (PUND) process.…”

Suppressing the ferroelectric switching barrier in hybrid improper ferroelectrics

“…Though these coercive fields are comparable to values suitable for integration to silicon chips (E c ≈ 50 kV cm −1 ), applications such as high-power actuators and low-voltage logic and memory elements ask for ferroelectrics with robust polarizations that can be switched by a lower coercive field [12][13][14][15] . Ultra-low coercive fields as low as 5 kV cm −1 were observed in pulsed laser deposition grown Ca 3 Ti 2 O 7 thin films, but the reason behind this reduction (and whether it is an intrinsic or an extrinsic effect) is not clarified yet 16 .…”