arXiv subjects

Jordan Hobbs

Publications and source records attributed to Jordan Hobbs.

16 recordsLinked to original sources

arXiv2026

Broken Inversion Symmetry via a Magic Methyl Effect

Polar liquid crystals - fluid phases in which molecular dipoles organise into ferro- or antiferroelectric states - present a highly constrained molecular design space, where small changes can entirely suppress polar organisation. Here we demonstrate, contrary to expectations, that installation of a methyl group in the 5-position of a 1,3-dioxane ring substantially increases the onset temperature of polar order. Remarkably, this effect proves transferable across several liquid-crystal families, including examples where the methylated derivative exhibits a polar phase whereas its parent compound does not. Across 8 matched pairs, we find that a 5-methyl group can enhance the onset temperature of polar order in 1,3-dioxane materials by up to 120 {\deg}C. These findings establish a simple and general molecular design strategy for enhancing and enabling spontaneous dipolar ordering in liquid crystals.

cond-mat.mtrl-sci↗

arXiv2026

Direct visualization of local electric fields in a layer of a ferroelectric nematic liquid

Ferroelectric nematic liquids exhibit complex ferroelectric domains shaped by competing elastic and electrostatic interactions. Using fluorescence and polarizing optical microscopy, we investigate domain formation and evolution under different anchoring conditions. Charged fluorescent ions map the electrostatic potential, revealing that electric fields are localized near domain walls and material surfaces. Upon cooling, domain walls transform from Ising- to N\'eel-type configurations, lowering the electrostatic potential, and reversibly recover upon heating.

cond-mat.soft↗

arXiv2026

Exotic topological defects and director fields in free-floating spherical ferroelectric nematic liquid crystal shells

Ferroelectric nematic (NF) liquid crystals exhibit polar symmetry and large polarization, giving rise to phenomena absent in conventional apolar nematics. We investigate NF liquid crystals confined to free-floating spherical shells with tangential boundary conditions, enforcing a total topological defect charge of +2. We conjecture that ferroelectric nematics avoid splayed configurations with half-integer defects, common in apolar nematic shells, instead concentrating the topological charge into escaped azimuthal +1 defects requiring only bend and twist. Indeed, at room temperature in the NF phase, our thin RM734+DIO shells with inner and outer aqueous poly(vinyl alcohol) solutions develop an azimuthal director field around two antipodal +1 bend-twist defects. The non-centrosymmetric nature and the azimuthal director configuration of the shells in the NF phase are confirmed also through second-harmonic generation microscopy. At intermediate temperature the antiferroelectric Nx phase generates a new exotic texture rife in zigzag lines in the shells. In the regular N phase at high temperature, the shells develop the usual four +1/2 disclinations located near the thinnest point. Our study highlights the rich platform offered by spherical shells to study the behavior of exotic liquid crystals subject to topological constraints, possibly opening new paths to apply the highly responsive ferroelectric nematic phase

cond-mat.soft↗

arXiv2026

Polarization Plasticity of Ferroelectric Nematics: a case of Electrostatic Frustration in Simple Planar Electrode Cells

Because of their spontaneous bulk polarization, ferroelectric nematic liquid crystals can be easily brought by surface coupling or confinement in a state in which the accumulation of bound charges becomes incompatible with polar order, creating frustration. This condition also occurs in the simplest cells with parallel uncoated metal electrodes where we find that the polarization charge accumulating on the electrodes is proportional to the applied voltage for $\Delta V< V_{sat}$, a threshold value independent of cell thickness. We show that below $V_{sat}$, frustration drives the system into a regime of polarization plasticity, in which nematic ordering is preserved and the nematic director remains perpendicular to the electrodes, while instead the polarization is reduced to cancel the internal electric field. In this regime, the kinetics of bound charge reversal becomes independent from $\Delta V$. The observations are consistent with a model in which the system splits into antipolar tubular domains of mesoscale diameter extending from electrode to electrode, in which the polarization retains its unconstrained equilibrium value, separated by pure polarization-reversal walls.

cond-mat.soft↗

arXiv2026

Design Principles for Fluid Molecular Ferroelectrics

Fluid molecular ferroelectrics are a new class of organic materials where ferroelectricity is found in conjunction with 3D fluidity whilst still retaining spontaneous polarization values comparable to their traditional solid state counterparts. One of the major challenges for soft condensed matter physics is predicting whether a fluid molecular material will form ferroelectric phase with nematic or smectic order. Through the synthesis of forty five systematically varied molecules, and by analogy to solid molecular ferroelectrics, is it shown that subtle hydrogen fluorine substitution allows for tuneable syn-parallel pairing motifs resulting in either specific pairings leading too geometrically constrained lamellar order or diversified pairings stabilising nematic ordering. Large-scale, fully atomistic molecular dynamics simulations reveal that smectic ferroelectricity emerges from discrete lateral pairing modes, whereas nematic phases arise from a multiplicity of equivalent polar configurations. Together, these findings establish experimentally validated design principles for fluid molecular ferroelectrics and provide a predictive framework for engineering functional polar fluids.

cond-mat.soft↗

arXiv2026

Flexoelectricity-driven softening of bend elasticity leads to spontaneous chiral symmetry breaking in a polar fluid

The origin of recently observed spontaneous chiral symmetry breaking in polar fluids is an unsolved problem, and poses fundamental questions as to how heliconical structures emerge in systems composed of achiral molecules. We report on the softening of bend elasticity close to such phase transition, showing that flexoelectric coupling between the electric polarization and the bend deformation is the responsible mechanism, presumably arising from the bent shape of the constituent highly polar molecules.

cond-mat.soft↗

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

Deep learning directed synthesis of fluid ferroelectric materials

Fluid ferroelectrics, a recently discovered class of liquid crystals that exhibit switchable, long-range polar order, offer opportunities in ultrafast electro-optic technologies, responsive soft matter, and next-generation energy materials. Yet their discovery has relied almost entirely on intuition and chance, limiting progress in the field. Here we develop and experimentally validate a deep-learning data-to-molecule pipeline that enables the targeted design and synthesis of new organic fluid ferroelectrics. We curate a comprehensive dataset of all known longitudinally polar liquid-crystal materials and train graph neural networks that predict ferroelectric behaviour with up to 95% accuracy and achieve root mean square errors as low as 11 K for transition temperatures. A graph variational autoencoder generates de novo molecular structures which are filtered using an ensemble of high-performing classifiers and regressors to identify candidates with predicted ferroelectric nematic behaviour and accessible transition temperatures. Integration with a computational retrosynthesis engine and a digitised chemical inventory further narrows the design space to a synthesis-ready longlist. 11 candidates were synthesised and characterized through established mixture-based extrapolation methods. From which extrapolated ferroelectric nematic transitions were compared against neural network predictions. The experimental verification of novel materials augments the original dataset with quality feedback data thus aiding future research. These results demonstrate a practical, closed-loop approach to discovering synthesizable fluid ferroelectrics, marking a step toward autonomous design of functional soft materials.

cond-mat.soft↗

arXiv2025

Ferroelectric Fluids for Nonlinear Photonics: Evaluation of Temperature Dependence of Second-Order Susceptibilities

Ferroelectric nematic fluids are promising materials for tunable nonlinear photonics, with applications ranging from second harmonic generation to sources of entangled photons. However, the few reported values of second-order susceptibilities vary widely depending on the molecular architecture. Here, we systematically measure second-order NLO susceptibilities of five different materials that exhibit the ferroelectric nematic phase, as well as the more recently discovered layered smectic A ferroelectric phase. The materials investigated include archetypal molecular architectures as well as mixtures showing room-temperature ferroelectric phases. The measured values, which range from 0.3 to 20 pm/V, are here reasonably predicted by combining calculations of molecular-level hyperpolarizabilities and a simple nematic potential, highlighting the opportunities of modelling-assisted design for enhanced NLO ferroelectric fluids.

cond-mat.soft↗

arXiv2025

Polarity from the Bottom Up: A Computational Framework for Predicting Spontaneous Polar Order

So-called polar liquid crystals possess spontaneous long-range mutual orientation of their electric dipole moments, conferring bulk polarity to fluid phases of matter. The combination of polarity and fluidity leads to complex phase behaviour, and rich new physics, yet the limited understanding around how specific molecular features generate long-range polar ordering in a fluid is a hindrance to development of new materials. In this work, we introduce a computational framework that probes the bimolecular potential energy landscape of candidate molecules, enabling us to dissect the role of directional intermolecular interactions in establishing polar order. In closely related families of materials we find conflicting preferences for (anti)parallel ordering which can be accounted for by specific interactions between molecules. Thus, our results allow us to argue that the presence (or absence) of polar order is a product of specific molecular features and strong directional intermolecular interactions rather than being simply a product of dipole-dipole forces. The design principles established can be leveraged to developing new polar liquid crystalline materials.

cond-mat.soft↗

arXiv2025

Ferri- and Ferro-Electric Switching in Spontaneously Chiral Polar Liquid Crystals

The recent discovery of spontaneous chiral symmetry breaking has demonstrated the possibility of discovering the exotic textures of ferromagnetic systems in liquid crystalline fluid ferro-electrics. We show that the polar smectic mesophase exhibited by the first molecule discovered to exhibit a spontaneously chiral ferroelectric nematic phase is also helical has a strongly varied textural morphology depending in its thermal history and phase ordering. Electro-optic studies demonstrate that the two spontaneously chiral phases exhibit field induced phase transitions. For the nematic variant, this process is threshold-less and has no hysteresis while for the smectic it has a clear threshold and shows hysteresis meaning this phase exhibits pseudo-ferrielectric switching, the first of its kind for ferroelectric nematic like phases. We show that helix formation can be both 1st and 2nd order but when it is 1st it is accompanied by pre-transitional helix formation in the preceding ferroelectric nematic phase.

cond-mat.soft↗

arXiv2025

Reactive Fluid Ferroelectrics: A Gateway to the Next Generation of Ferroelectric Liquid Crystalline Polymer Networks

Herein we report the first examples of reactive mesogenic materials (RMs) which exhibit fluid ferroelectric order based on the recently discovered ferroelectric nematic (NF) phase. We term these materials NF RMs and they provide the first steps towards the next generation of ferroelectric liquid crystalline polymer networks. We report the chemical synthesis and characterisation of the liquid crystalline properties of these materials, demonstrating that they have the lowest longitudinal molecular dipole moments of any reported NF material of 7.39 D. We go on to demonstrate a potential use case of this new class of reactive material through the polymer stabilisation of a matrix which exhibits the NF phase, increasing the phase range of the ferroelectric phase from 75 {\deg}C to 120 {\deg}C. The NF RMs reported herein are an exciting step forward in ferroelectric liquid crystal research, demonstrating that reactive NF materials are achievable, allowing for the future development of liquid crystalline ferroelectric networks, elastomers and polymers.

cond-mat.mtrl-sci↗

arXiv2024

Systematic Fluorination is a Powerful Design Strategy Towards Fluid Molecular Ferroelectrics

Ferroelectric nematic (NF) liquid crystals combine liquid-like fluidity and orientational order of conventional nematics with macroscopic electric polarization comparable in magnitude to solid state ferroelectric materials. Here, we present a systematic study of twenty-seven homologous materials with various fluorination patterns, giving new insight into the molecular origins of spontaneous polar ordering in fluid ferroelectric nematics. Beyond our initial expectations, we find the highest stability of the NF phase to be in materials with specific fluorination patterns rather than the maximal fluorination which might be expected based on simple models. We find a delicate balance between polar and apolar nematics which is entirely dictated by the substitution of the fluorine atoms. Aided by electronic structure calculations, we show this to have its origins in the radial distribution of charge across the molecular surface, with molecules possessing a more oscillatory distribution of electrons across their surfaces possessing a higher propensity to form polar nematic phases. This work provides a new set of ground rules and designing principles which can inform the synthesis of future ferroelectric nematogens.

cond-mat.soft↗

arXiv2024

Polar order in a fluid like ferroelectric with a tilted lamellar structure -- observation of a polar smectic C (SmC${_\textrm{P}}$) phase

The discovery of fluid states of matter with spontaneous bulk polar order is appreciated as a major discovery in the fields of soft matter and liquid crystals. Typically, this manifests as polar order superimposed atop conventional phase structures and is thus far limited to orthogonal phase types. Here we report a family of materials which exhibit a previously unseen state of matter which we conclude is a polar smectic C phase, and so we term it SmC${_\textrm{P}}$. The spontaneous polarisation of the SmC${_\textrm{P}}$ phase is over two orders of magnitude larger than that found in conventional ferroelectric SmC phase of chiral materials used in some LCD devices. Fully atomistic molecular dynamics simulations faithfully and spontaneously reproduce the proposed structure and associated bulk properties; comparison of experimental and simulated X-ray scattering patterns shows excellent agreement. The materials disclosed here have significantly smaller dipole moments than typical polar liquid crystals such as RM734 which suggests the role of molecular electrical polarity in generating polar order is perhaps overstated, a view supported by consideration of other molecular systems.

cond-mat.soft↗

arXiv2024

Emergent Anti-Ferroelectric Ordering and the Coupling of Liquid Crystalline and Polar Order

Polar liquid crystals possess three dimensional orientational order coupled with unidirectional electric polarity, yielding fluid ferroelectrics. Such polar phases are generated by rod-like molecules with large electric dipole moments. 2,5-Disubstituted 1,3-dioxane is commonly employed as a polar motif in said systems, and here we show this to suffer from thermal instability as a consequence of equatorial-trans to axial-trans isomerism at elevated temperatures. We utilise isosteric building blocks as potential replacements for the 1,3- dioxane unit, and in doing so we obtain new examples of fluid ferroelectric systems. For binary mixtures of certain composition, we observe the emergence of a new fluid antiferroelectric phase - a finding not observed for either of the parent molecules. Our study also reveals a critical tipping point for the emergence of polar order in otherwise apolar systems. These results hint at the possibility for uncovering new highly ordered polar LC phases and delineate distinct transition mechanisms in orientational and polar ordering.

cond-mat.soft↗

arXiv2024

Spontaneous Symmetry Breaking in Polar Fluids

Spontaneous symmetry breaking and emergent polar order are each of fundamental importance to a range of scientific disciplines, as well as generating rich phase behaviour in liquid crystals (LCs). Here, we show the union of these phenomena to lead to two previously undiscovered polar liquid states of matter. Both phases have a lamellar structure with an inherent polar ordering of their constituent molecules. The first of these phases is characterised by polar order and a local tilted structure; the tilt direction precesses about a helix orthogonal to the layer normal, the period of which is such that we observe selective reflection of light. The second new phase type is anti-ferroelectric, with the constituent molecules aligning orthogonally to the layer normal. This has led us to term the phases the SmC_P^H and SmAAF phases, respectively. Further to this, we obtain room temperature ferroelectric nematic (NF) and SmC_P^Hphases via binary mixture formulation of the novel materials described here with a standard NF compound (DIO), with the resultant materials having melting points (and/or glass transitions) which are significantly below ambient temperature.

cond-mat.soft↗