Scientists demonstrate a fluid that couples electric and magnetic order at room temperature, introducing a soft multiferroic platform for reconfigurable sensing, actuation, and field-controlled material behavior.
(Nanowerk Spotlight) Materials that can respond to both electric and magnetic fields hold enormous promise for next-generation technologies—from reconfigurable electronics to energy-efficient sensors. But designing a single substance that naturally supports both electric and magnetic order has proved unusually difficult. In solids, the problem is structural: the atomic arrangements that favor switchable electric polarization tend to suppress magnetism, and vice versa.
This conflict has limited engineers to fragile workarounds—gluing together separate ferroelectric and magnetic layers, or coaxing weak responses from exotic compounds. The result is a field full of technical complexity but short on practical, adaptable materials.
Liquids offer an entirely different route. Unlike rigid crystals, they can flow, self-heal, and adapt to their environment. Until recently, though, liquids were considered too disordered to support the kind of long-range ordering needed for magnetic or electric polarity. That changed with two discoveries.
One was a fluid made from magnetic nanoplatelets suspended in a liquid crystal, which spontaneously aligns to form a magnetized state. The other was a class of rod-shaped molecules that organize into ferroelectric nematic liquids—fluids that carry a built-in electric polarization, much like their solid counterparts. Each was a major step. But no system had combined both behaviors in the same material.
Now, researchers at Otto von Guericke University in Magdeburg, Germany, have demonstrated a fluid that does exactly that. By embedding magnetic nanoplatelets into a ferroelectric nematic host, they created the first known liquid that simultaneously exhibits electric and magnetic order at room temperature. This hybrid not only demonstrates coupling between the two properties, but does so in a soft, reconfigurable phase—opening a path to stimulus-sensitive materials for use in sensing, soft robotics, and adaptive optics.
Fluids with orientational order: a) isotropic suspensions of BaHF nanoplatelets in 1-butanol form b) the colloidal ferromagnetic nematic phase at a sufficiently high volume fraction. c) Ferromagnetic nematic phase occurs in dispersions of the nanoplatelets in a thermotropic nematic. d) Thermotropic nematogens can form the nematic phase N with a cylindric symmetry. e) In some compounds, the director invariance is broken, resulting in the ferroelectric nematic phase NF with the director’s polar symmetry. (Image: Reprinted from DOI:10.1002/adma.202508406, CC-BY) (click on image to enlarge)
To build the hybrid system, the team suspended ferrimagnetic barium hexaferrite (BaHF) nanoplatelets into a ferroelectric nematic liquid crystal known as M5. The resulting composite retains the spontaneous polarization of the ferroelectric host and acquires additional magnetic functionality from the nanoplatelets. Concentrations from 0.3 to 4.0 weight percent were tested, with the highest stable concentration just below the threshold where particle aggregation becomes unavoidable.
The system remains stable through multiple thermal transitions in the host liquid crystal, including the low-temperature ferroelectric nematic phase and the intermediate antiferroelectric phase. The added nanoparticles did not shift these phase boundaries significantly. Instead, they integrated into the host’s orientational field through a combination of elastic, electrostatic, and anchoring interactions. This integration allowed them to form extended structures that respond coherently to electric and magnetic fields.
One key structural feature of the hybrid material is the formation of disclination lines—topological defects in the alignment of the liquid crystal molecules. These lines are not just passive features. In this system, they act as scaffolds for organizing the magnetic nanoplatelets. Optical microscopy revealed a network of such lines, which rearranged under applied magnetic fields. The network showed memory effects and polarity-sensitive responses, indicating that the system retained a preferred magnetic state even when the field was removed.
The researchers confirmed ferromagnetic behavior through magnetization measurements, which showed hysteresis loops consistent with stable magnetic domains. They also demonstrated that the system responded electrically to changes in magnetic field. When a magnet passed over the fluid or when it was placed in a rotating magnetic field, the material generated an electric current. This is a clear indication of direct magnetoelectric coupling—a central requirement for classifying the material as multiferroic.
Conversely, they applied electric fields and detected magnetic changes using a fluxgate sensor. The signals were smaller and decayed over time, likely due to particle diffusion and reorientation in the fluid. Still, the presence of both direct and converse effects confirms the bidirectional coupling between the electric and magnetic order parameters in the fluid phase.
Additional insights came from nonlinear optics. The researchers used second harmonic generation (SHG) microscopy to probe the polar structure of the fluid. In the ferroelectric nematic phase, the SHG signal was strong and spatially varied, revealing domains with aligned polarization. When a magnetic field was applied, these domains changed shape and intensity, indicating that the polar structure of the fluid could be reoriented by magnetic forces.
The coupling mechanism depends on how the magnetic nanoplatelets align with the liquid crystal director—the average orientation of the surrounding molecules. Depending on the surface anchoring, the director can point tangentially or perpendicularly to the platelets. These arrangements produce localized distortions in the electric polarization field, which lead to dipolar interactions and the formation of chains or loops. In confined geometries, the particles assemble into networked structures that propagate changes across the system when fields are applied.
The dynamics of the hybrid material were further tested under oscillating magnetic fields. Even at low field amplitudes, the system showed clear changes in optical transmission. These changes followed the frequency of the applied field, confirming that the material’s internal order could track external perturbations in real time. Relaxation rates measured by AC susceptometry were more than two orders of magnitude slower than in comparable isotropic suspensions, indicating that the liquid crystal structure strongly constrains particle motion.
Despite the promising results, the electric-to-magnetic coupling remains weaker than the magnetic-to-electric response. The authors suggest that this asymmetry may be due to the irregular geometry of the defect network and the difficulty of reorienting nanoplatelets once they are embedded in the disclination lines. Improvements in particle design—such as using Janus particles with asymmetric surface properties—could enhance alignment and boost coupling strength.
The study introduces a platform for creating fluid systems with coexisting electric and magnetic order that are stable, reconfigurable, and operational at room temperature. Unlike solid-state multiferroics, which often require careful crystal engineering and suffer from mechanical constraints, this hybrid fluid can be shaped into thin films or emulsions and remains sensitive to external fields without rigid substrates or fixed geometries.
By combining ferromagnetic nanoplatelets with a ferroelectric nematic host, the researchers have demonstrated a liquid-phase material that fulfills the criteria for multiferroic behavior. It offers both responsiveness and adaptability, expanding the landscape of soft matter physics and pointing toward practical applications in areas where flexibility, reconfigurability, and stimulus sensitivity are essential.
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