Tunable topological chirality in ferroelectric nanomaterials
Chirality is one of the most intriguing fundamental phenomena in nature. Materials composed of chiral molecules find broad applications in areas ranging from nonlinear optics and spintronics to biology and pharmaceuticals. However, chirality is usually an invariable inherent property of a given material that cannot be easily changed at will. Very recently we discovered that chiral structure emerges as a basic configuration of polarization field in ferroelectric nanoparticles and nanodots in a form of stable fundamental topological excitations of polarization, Hopfions, and skyrmions, and, importantly, can be controlled and switched by cleverly devised field-temperature protocols. The key idea of the project is to reveal how this discovered emerging topological chirality will be identified, measured, explored, and put in practice.
The ferroelectric FET with negative capacitance
Integrating negative capacitance into the field-effect transistors (FET) promises to break fundamental limits of power dissipation known as Boltzmann tyranny. Here we put forth an ingenious design for the ferroelectric domain-based FET with the stable reversible static negative capacitance.
Data were published in Communications Physics 2, 22 (2019)
Here we report a mechanism wiping out the polarization discontinuity (appearing when antiparallel domains meet) in the uniaxial ferroelectrics possessing low domain wall conductivity. This mechanism consists in forming the specific configuration of the polarization vector field with the mutual domain bifurcation. It creates the characteristic saddle-point domain wall morphology removing the need for the screening charge accumulation and associated conductivity enhancement.
Here we investigate the domain structure in the SrTiO3/PbTiO3/SrTiO3 heterostructures and demonstrate that the temperature-thickness phase diagram of the system includes the ferroelectric and paraelectric regions, which exhibit different responses to the applied electric field.
Here we study the polar and nonpolar instabilities in the preformation of ferroelectric transition in SrTiO3 under perturbations, deviating the system from quantum paraelectric toward the classic ferroelectric phase.
Here we put forth an ingenious design for the ferroelectric domain-based field-effect transistor with stable reversible static negative capacitance. Using a dielectric coating of the ferroelectric capacitor enables the tunability of the negative capacitance improving tremendously the performance of the field-effect transistors.
Here we investigate the Pb-doped SrTiO3 solid solutions, approaching the pre-critical regions of the phase diagram and study the outcome of the coexistence of quantum fluctuations and thermal motion.
Here we devise protocols for realizing control and efficient manipulations of the skyrmions with different chirality in ferroelectric nanodots. Our findings open the route for controlled chirality with potential applications in ferroelectric-based information technologies.
Paradigmatic knotted solitons, Hopfions, that are characterized by topological Hopf invariant, attract an intense attention in the diverse areas of physics ranging from high-energy physics, cosmology and astrophysics to biology, magneto- and hydrodynamics and condensed matter physics. Yet, while being of broad interest, they remain elusive and under-explored. Here we demonstrate that Hopfions emerge as a basic configuration of polarization field in confined ferroelectric nanoparticles. Our findings establish that Hopfions are of fundamental importance for the electromagnetic behavior of the nanocomposits and can result in advanced functionalities of these materials.
Here, we show that the ferroelectric nanodot capacitor hosts a stable two-domain state realizing the static reversible negative capacitance device thus opening routes for the extensive use of the negative capacitance in domain wall-based nanoelectronics.
A method employs a device with a heterostructure as a resonator for electrons of an electrical circuit or for a terahertz electromagnetic wave. The heterostructure comprises at least one dielectric layer and at least one ferroelectric layer. The at least one ferroelectric layer comprises a plurality of ferroelectric polarization domains. The plurality of ferroelectric polarization domains forms a polarization pattern. The polarization pattern is adapted to perform an oscillation with a resonance frequency in a terahertz frequency range. The method comprises functionally coupling the oscillation of the polarization pattern and an oscillation of the electrons of the electrical circuit or of the terahertz electromagnetic wave by the device.
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e-mail: anna.razumnaya@ijs.si
