Electric field control of chirality

Abstract

Polar textures have attracted substantial attention in recent years as a promising analog to spin-based textures in ferromagnets. Here, using optical second-harmonic generation-based circular dichroism, we demonstrate deterministic and reversible control of chirality over mesoscale regions in ferroelectric vortices using an applied electric field. The microscopic origins of the chirality, the pathway during the switching, and the mechanism for electric field control are described theoretically via phase-field modeling and second-principles simulations, and experimentally by examination of the microscopic response of the vortices under an applied field. The emergence of chirality from the combination of nonchiral materials and subsequent control of the handedness with an electric field has far-reaching implications for new electronics based on chirality as a field-controllable order parameter.

Melting of Polarization Vortices Crystals and Chiral Phase Transitions in Oxide Superlattices

“…Similar domain size disproportionation has been found in PbTiO 3 /SrTiO 3 superlattices [7] at planes where dislocation points formed by pair of nearby concave and convex disclinations appear [25]. They have also been experimentally observed at chiral domain boundaries [21]. Moreover, modulation of the vortices by a second ordering along their axial direction have been recently reported in PbTiO 3 /SrTiO 3 superlattices grown on a metallic SrRuO 3 substrate [33].…”

“…1(a)] we observe a continuously rotating polarization configuration in the (x, z) plane, forming a long-range ordered array of clockwise and counter clockwise vortex pairs within the PbTiO 3 layer. An axial component of the polarization is clearly detected in our simulations, making the full system to be chiral [19][20][21] with a well defined handedness. This structure is independent of the plane considered along the axial y-direction, so the vortex appearance can be described as perfect tubes in a 3D framework.…”

“…Indeed, these structures present an underlying coarse grain ordering often associated with the way in which the topological defects arrange in the supercell. These new states of matter, such as vortices or skyrmions, come together with exotic functional properties, such as negative capacitance [16][17][18] or chirality [18][19][20][21]. Therefore, the evolution of both the structural and the asso-ciated functional properties with external stimuli, such as electric fields, mechanical strain, or thermal fluctuations, is an important question from the applied and the fundamental point of view.…”

“…1). An axial component of the polarization along the y-direction (perpendicular to the plane defined by the vortices) might coexist with the vorticity, imposing a handedness to each individual vortex [19][20][21]. Several studies have analyzed the effect on the structure of the periodicity, epitaxial strain, or electric field.…”

Phase Diagram of a Strained Ferroelectric Nanowire

“…On top of that, chirality, a new functionality of confined ferroelectrics, has recently received explosive interest [16,17,58,59]. The newly discovered polarization chirality of nanowires, including its unprecedented tunability by the strains and temperature, opens a broad spectrum of fascinating directions promising to revolutionize different technological fields ranging from plasmonic and photonics relevant for quantum optoelectronic communications to chemical, pharmaceutical, and biomedical applications.…”