Self-assembling peptides (SAPs) have been extensively studied for their ability to form nanoscale ordered structures driven by noncovalent molecular interactions. Meanwhile, polymerization-induced self-assembly (PISA) has been exploited as a facile and efficient way to produce various amphiphilic block copolymer nano-objects, whose self-assembly was governed predominantly by the interactions of the different blocks with the polymerization medium. In this work, we combined PISA with SAPs to prepare novel peptide–polymer hybrid nano-objects, thus harnessing the advantages of PISA and the self-assembling driving force of SAPs. A tripeptide methacrylamide derivative (MAm-Gly-Phe-Phe-NH2, denoted as MAm-GFF, where MAm means methacrylamide) was copolymerized with glycerol monomethacrylate (GMA) to produce a P(GMA65-stat-(MAm-GFF)7) macro-chain transfer agent (macro-CTA) by reversible addition–fragmentation chain transfer polymerization in dimethylformamide. This peptide-based macro-CTA was then successfully chain-extended with poly(2-hydroxypropyl methacrylate) (PHPMA) by aqueous dispersion PISA, forming P(GMA65-stat-(MAm-GFF)7)-b-PHPMA28 self-assembled objects. Fibrous structures were observed by transmission electron microscopy (TEM) and Cryo-TEM, in agreement with depolarized dynamic light scattering, static light scattering, and small-angle X-ray scattering experiments that also revealed long anisotropic morphologies. Such structures have not been reported previously for PISA-prepared nano-objects. This confirms the decisive influence of the GFF SAP on the self-assembly. In addition, annealing the PISA suspension at different temperatures led to a significant size decrease in the self-assembled objects and to a morphological transition caused by the thermosensitivity of both the core-forming PHPMA block and the stabilizing P(GMA-stat-(MAm-GFF)) block.

Chirality, a foundational concept throughout science, may arise at ferromagnetic domain walls 1 22 and in related objects such as skyrmions 2. However, chiral textures should also exist in other types 23 of ferroics such as antiferromagnets for which theory predicts that they should move faster for 24 lower power 3 , and ferroelectrics where they should be extremely small and possess unusual 25 topologies 4,5. Here we report the concomitant observation of antiferromagnetic and electric chiral 26 textures at domain walls in the room-temperature ferroelectric antiferromagnet BiFeO 3. 27 Combining reciprocal and real-space characterization techniques, we reveal the presence of 28 periodic chiral antiferromagnetic objects along the domain walls as well as a priori energetically 29 unfavorable chiral ferroelectric domain walls. We discuss the mechanisms underlying their 30 formation and their relevance for electrically controlled topological oxide electronics and 31 spintronics. 32 33 Metallic ferromagnets have been the elemental bricks of spintronics for the last three decades and 34 continue to hold promises on the basis of non-collinear chiral spin textures such as skyrmions. These 35 topologically protected objects are envisioned to be the future of magnetic data storage thanks to 36 their specific stability, dynamics, and scalability 2. In parallel, antiferromagnets (AFs) are emerging as a 37 new paradigm for spintronics 6. They are intrinsically stable (being insensitive to spurious magnetic 38 fields), scalable (no cross talk between neighbouring memory cells), and fast (switching frequencies 39 in the THz regime). The opportunity of gathering the best of these two worlds and realize 40 "antiferromagnetic skyrmions" is then tremendously appealing but faces at least two major 41 challenges. The first one is to achieve antiferromagnetic chirality and the second one is to identify 42 appropriate control stimuli to create, annihilate and move these chiral objects. 43 On one hand, chirality may naturally emerge at domain walls. The antiferromagnetic domain wall 44 structure is a virtually uncharted territory but this is where translational symmetry is broken and spin 45 rotation favoured. On the other hand, AF manipulation is hampered by the intrinsic lack of net 46 magnetization, which prevents a straightforward magnetic actuation. This fundamental issue may be 47

We exploit the deformation of drops spinning in a denser background fluid to investigate the effective interfacial tension (EIT) between miscible molecular fluids. We find that, for sufficiently low interfacial tension, spinning drops develop dumbbell shapes, with two large heads connected by a thinner central body. We show that this shape depends not only on the density and viscosity contrast between the drop and background fluids, but also on the fluid molecular structure, and hence on the stresses developing at their interface due to a different molecular interaction. We systematically investigate the dynamics of dumbbell-shaped drops of water-glycerol mixtures spinning in a pure glycerol reservoir. By developing a model for the deformation based on the balance of the shear stress opposing the deformation, the imposed normal stress on the drop, and an effective interfacial tension, we exploit the time evolution of the drop shape to measure the EIT. Our results showthat the EIT in water-glycerol systems is orders of magnitude lower than that reported in previous experimental measurements, and in excellent agreement with values calculated via the phase field model proposed by Truzzolillo et al. [Phys. Rev. X 6, 041057 (2016)].

We study the near-field radiative heat transfer between two twisted finite-size polar dielectric nanoparticle gratings. Different from previ- ous studies of the same configuration, we do not rely on any approximated effective medium theory to describe the gratings. By the full many-body radiative heat transfer theory, we are able to investigate how the size, distance, and relative orientation between the gratings influence the radiative heat flux. By changing the twisting angle h, we show a significant oscillation of the thermal conductance G(\theta), due to the size effect for gratings of both square and circular shapes. The distance- and twisting-dependent coupling between the gratings accounts for a strong and characteristic modulation of radiative thermal conductance with implications for the energy management, sensing, and the micro-electromechanical system (MEMS) and nano-electromechanical system (NEMS) devices.

Antiferromagnetic thin films are currently generating considerable excitement for low dis-sipation magnonics and spintronics. However, while tuneable antiferromagnetic textures form the backbone of functional devices, they are virtually unknown at the submicron scale. Here we image a wide variety of antiferromagnetic spin textures in multiferroic BiFeO 3 thin films that can be tuned by strain and manipulated by electric fields through room-temperature magnetoelectric coupling. Using piezoresponse force microscopy and scanning NV magne-tometry in self-organized ferroelectric patterns of BiFeO 3 , we reveal how strain stabilizes different types of non-collinear antiferromagnetic states (bulk-like and exotic spin cycloids) as well as collinear antiferromagnetic textures. Beyond these local-scale observations, resonant elastic X-ray scattering confirms the existence of both types of spin cycloids. Finally, we show that electric-field control of the ferroelectric landscape induces transitions either between collinear and non-collinear states or between different cycloids, offering perspectives for the design of reconfigurable antiferromagnetic spin textures on demand.

Ultraviolet microdisk lasers are integrated monolithi-cally into photonic circuits using a III-nitride on silicon platform with gallium nitride (GaN) as the main waveguiding layer. The photonic circuits consist of a microdisk and a pulley waveguide terminated by out-coupling gratings. We measure quality factors up to 3500 under continuous-wave excitation. Lasing is observed from 374 nm to 399 nm under pulsed excitation, achieving low threshold energies of 0.14 mJ/cm 2 per pulse (threshold peak powers of 35 kW/cm 2). A large peak to background dynamic of around 200 is observed at the out-coupling grating for small gaps of 50 nm between the disk and waveguide. These devices operate at the limit of what can be achieved with GaN in terms of operation wavelength.

we report the development of a scanning confocal microscope dedicated to photoluminescence in the 200 nm-wavelength range for samples at cryogenic temperatures (5-300K). We demonstrate the performances of our deep ultraviolet cryomicroscope in high- quality hexagonal boron nitride (hBN) crystals, although it can be utilized for biological studies in its range of operating wavelengths. From the mapping of the photoluminescence, we bring evidence for the suppression of extrinsic recombination channels in regions free from defects. The observation of emission spectra dominated by intrinsic recombination processes was never reported before in hBN, by means of photoluminescence spectroscopy. We show that photoluminescence tomography now competes with cathodoluminescence, and that deep ultraviolet cryomicroscopy by photoluminescence is a novel powerful tool in materials science applications, with the great advantage of an efficient non-invasive photo- excitation of carriers.