arXiv subjects

Peter Medle Rupnik

Publications and source records attributed to Peter Medle Rupnik.

4 recordsLinked to original sources

arXiv2026

Modulated Anti-Ferroelectric Smectic Phases with Orthogonal and Tilted Structures

The discovery of the ferroelectric nematic phase has brought with it a plethora of new polar liquid crystalline phases. One in particular is the anti-ferroelectric smectic A SmA\textsubscript{AF} phase. In this letter we show via observation and analysis of satellite peaks in the X-ray scattering pattern that the structure of the SmA\textsubscript{AF} phase involves a density modulation of $\approx$10-20 nm lateral to the smectic layer normal. Further, we demonstrate a previously undiscovered phase where the anti-ferroelectric order is maintained into a tilted smectic phase demonstrating the robustness of the underlying frustration that leads to the modulated structure. We suggest that the modulations are only in a single dimension and appear parallel to the tilt plane. This new phase also shows a significantly different and complex response to an electric field from other discovered polar LC phases due to the ability to modulate both tilt and polarisation direction.

cond-mat.soft↗

arXiv2025

Nanostructured multiferroic liquids: on the way to fluid ferroelectric magnets

Responsiveness to multiple stimuli and adaptivity are paramount for designing smart multifunctional materials. In soft, partially ordered systems, these features can often be achieved via self-assembly, allowing for the combination of diverse components in a complex nanostructured material. Here, we demonstrate an example of a liquid that simultaneously displays both ferroelectric and ferromagnetic types of order. This material is a nanostructured liquid crystalline hybrid comprising ferrimagnetic barium hexaferrite nanoplatelets suspended in a ferroelectric nematic host. Director-mediated interactions drive the self-assembly of nanoplatelets in an intricate network. Due to the couplings between the polar electric and magnetic types of order, this material demonstrates magnetically driven electric and nonlinear optical responses, as well as electrically driven magnetic response. Such multiferroic liquids are highly promising for applications in energy harvesting, nonlinear optics, and sensors.

cond-mat.soft↗

arXiv2025

Antiferroelectric order in nematic liquids: Flexoelectricity vs electrostatics

The recent discovery of ferroelectric nematic liquid crystalline phases marks a major breakthrough in soft matter research. An intermediate phase, often observed between the nonpolar and the ferroelectric nematic phase, shows a distinct antiferroelectric response to electric fields. However, its structure and formation mechanisms remain debated, with flexoelectric and electrostatics effects proposed as competing mechanisms. By controlling the magnitude of electrostatic forces through ion addition in two representative ferroelectric nematic materials, we show that the primary mechanism for the emergence of antiferroelectric order is the flexoelectric coupling between electric polarization and splay deformation of the nematic director. The addition of ions significantly expands the temperature range over which the antiferroelectric phase is observed, with this range increasing with increasing ion concentration. Polarizing optical microscopy studies and second harmonic generation microscopy reveal the splayed structure modulated in two dimensions, while SHG interferometry confirms its antiferroelectric character. We extend the model previously used to describe pretransitional behaviour by incorporating the electrostatic contribution of ions. The model shows qualitative agreement with the experiments, accurately reproducing the phase diagram and temperature-dependent evolution of the modulation period of the observed structure.

cond-mat.soft↗

arXiv2024

Viscous Mechano-Electric Response of Ferroelectric Nematic Liquid

Direct viscous mechano-electric response is demonstrated for a room-temperature ferroelectric nematic liquid, which combines large spontaneous electric polarization with 3D fluidity. The mechano-electric transduction is observed in the frequency range 1-200 Hz via a simple demonstrator device. The liquid is placed into a deformable container with electrodes and the electric current induced by both periodic and irregular actuation of the container is examined. The experiments reveal a rich interplay of several distinct viscous mechano-electric phenomena, where both shape deformations and material flow cause changes in the electric polarization structure of a ferroelectric nematic liquid. The results show that the mechano-electric features of the material promise a considerable applicative perspective spanning from sensitive tactile sensors to energy harvesting devices.

cond-mat.soft↗