Resonant domain-wall-enhanced tunable microwave ferroelectrics

Abstract

Ordering of ferroelectric polarization and its trajectory in response to an electric field are essential for the operation of non-volatile memories, transducers and electro-optic devices. However, for voltage control of capacitance and frequency agility in telecommunication devices, domain walls have long been thought to be a hindrance because they lead to high dielectric loss and hysteresis in the device response to an applied electric field. To avoid these effects, tunable dielectrics are often operated under piezoelectric resonance conditions, relying on operation well above the ferroelectric Curie temperature, where tunability is compromised. Therefore, there is an unavoidable trade-off between the requirements of high tunability and low loss in tunable dielectric devices, which leads to severe limitations on their figure of merit. Here we show that domain structure can in fact be exploited to obtain ultralow loss and exceptional frequency selectivity without piezoelectric resonance. We use intrinsically tunable materials with properties that are defined not only by their chemical composition, but also by the proximity and accessibility of thermodynamically predicted strain-induced, ferroelectric domain-wall variants. The resulting gigahertz microwave tunability and dielectric loss are better than those of the best film devices by one to two orders of magnitude and comparable to those of bulk single crystals. The measured quality factors exceed the theoretically predicted zero-field intrinsic limit owing to domain-wall fluctuations, rather than field-induced piezoelectric oscillations, which are usually associated with resonance. Resonant frequency tuning across the entire L, S and C microwave bands (1-8 gigahertz) is achieved in an individual device-a range about 100 times larger than that of the best intrinsically tunable material. These results point to a rich phase space of possible nanometre-scale domain structures that can be used to surmount current limitations, and demonstrate a promising strategy for obtaining ultrahigh frequency agility and low-loss microwave devices.

Strain Engineering a Multiferroic Monodomain in Thin-Film BiFeO3

“…Furthermore, from an experimental perspective the intrinsic properties of a prototypical device can be obscured by the presence of multiple domains, and would ideally be demonstrated within a single-domain architecture. Although exploiting particular combinations of domains can be advantageous [5][6][7][8], their population and the exact location of the domain boundaries must be controlled with great precision to realize the full potential of multiferroic materials.…”

Topology and control of self-assembled domain patterns in low-dimensional ferroelectrics

“…This is particularly relevant in the case of ferroic materials, where complex domain wall arrangements primarily drive emergent phenomena 4 . Understanding the intricate formation processes at play in the formation of modulated phases is thus pivotal for the development of future technologies, e.g., domain wall nanoelectronics [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]21,22 , a field of research that has recently seen fiery surge of interest. So far, modulated phases of ferroelectric domains such as the dipolar maze or labyrinthine phase 23 , and the nano-bubble or skyrmionic phase 21,22,24 have been somewhat regarded as conceptually disparate [24][25][26][27][28][29][30] .…”

Analytical Approach of Director Tilting in Nematic Liquid Crystals for Electronically Tunable Devices

“…dt dz 2 can be neglected from equation (3). Operating and separating into simple fractions, the differential equation (3) can be rewritten as…”

“…Controlling the radiation parameters of the antennas is one of the critical technological challenges that have arisen, since adaptive beamforming is expected to play an important role in 5G networks [1]. For this reason, new materials such as graphene [2], ferroelectrics [3] or liquid crystal (LC) [4] are beginning to be used for the design of microwave tunable devices.…”