Chiral magnets have recently emerged as hosts for topological spin textures and related transport phenomena, which can find use in next-generation spintronic devices. The coupling between structural chirality and noncollinear magnetism is crucial for the stabilization of complex spin structures such as magnetic skyrmions. Most studies have been focused on the physical properties in homochiral states favored by crystal growth and the absence of long-ranged interactions between domains of opposite chirality. Therefore, effects of the high density of chiral domains and domain boundaries on magnetic states have been rarely explored so far. Herein, we report layered heterochiral Cr1/3TaS2, exhibiting numerous chiral domains forming topological defects and a nanometer-scale helimagnetic order interlocked with the structural chirality. Tuning the chiral domain density, we discovered a macroscopic topological magnetic texture inside each chiral domain that has an appearance of a spiral magnetic superstructure composed of quasiperiodic Néel domain walls. The spirality of this object can have either sign and is decoupled from the structural chirality. In weak, in-plane magnetic fields, it transforms into a nonspiral array of concentric ring domains. Numerical simulations suggest that this magnetic superstructure is stabilized by strains in the heterochiral state favoring noncollinear spins. Our results unveil topological structure/spin couplings in a wide range of different length scales and highly tunable spin textures in heterochiral magnets.

Compared with the domain wall motion in a ferromagnetic nanowire, the chiral soliton motion could reach a much larger velocity at a much smaller current density. [9,11] The metallic chiral magnets that can host CSL are very rare. As far as we know, the formation of CSL in metallic chiral magnets has been only observed in Cr 1/3 NbS 2 and YbNi 3 Al 9 . [2,3,12,13] As the stability of chiral magnetic solitons is determined by the Dzyaloshinskii-Moriya (DM) interaction and the velocity of soliton motion is controlled by the non-adiabatic torque, searching for new chiral magnets associate with strong DM interaction and large non-adiabatic torque is of great importance in the emerging field of solitonics. [2,3,8,9] Among the various candidates, the magnetic ion (M = Cr, Mn, Fe, Co, and Ni) intercalated M 1/3 TaS 2 stands out because the parent compound TaS 2 has large spin-orbit coupling (SOC) and hosts a rich collection of exotic states including the Mott state, charge density wave, and quantum spin liquid. [14][15][16] As the magnetic ions insert into TaS 2 , the ordering of magnetic ions in M 1/3 TaS 2 results in a (1/3, 1/3, 0) superstructure with a chiral space group of P6 3 22. [17] The strong SOC and the chiral lattice structure of M 1/3 TaS 2 could induce strong DM interaction and large non-adiabatic torque, since the strength of DM interaction and non-adiabatic torque both are proportional to the SOC constant. [18,19] In the family of M 1/3 TaS 2 , only Fe 1/3 TaS 2 has been confirmed as a chiral magnet. [17,20] Nevertheless, the extremely large orbital magnetic moment of Fe 2+ ions yields the gigantic easy-axis magnetocrystalline anisotropy and brings on the Ising-type ferromagnetic structure in Fe 1/3 TaS 2 . [17,21] The crystal growth and characterization of several other M 1/3 TaS 2 have been studied as early as the 1980s, yet whether the crystals possess chiral lattice structure and chiral magnetism are in question. [22][23][24] For example, the Cr 1/3 TaS 2 has been reported to exhibit a trivial ferromagnetic (FM) transition near 115 K without any hints of chiral features. [22][23][24][25] In this work, we report the magneto-transport properties and magnetic phase diagrams of Cr 1/3 TaS 2 single crystals. In contrast with the reported trivial FM transition, our Cr 1/3 TaS 2 single crystals exhibit a chiral helimagnetic (CHM) transition near 140 K. The conducting electrons interact with the CHM and CSL orders, giving rise to the nontrivial magnetoresistance (MR) in Cr 1/3 TaS 2 . The normalized magnetic moment and Cr 1/3 TaS 2 -a candidate of chiral magnet-has been reported as a trivial ferromagnetic material. In contrast, the Cr 1/3 TaS 2 single crystals exhibit a chiral helimagnetic (CHM) transition near 140 K. The magnetic moment versus magnetic field curves reveal a CHM-chiral soliton lattice (CSL)-forced ferromagnetic (FFM) transition in the magnetic ordered state. The conducting electrons interact with the CHM and CSL orders, giving rise to the nontrivial magnetoresistance (MR) in the Cr 1/3 TaS 2 ...

Understanding the thermodynamics that drives liquid-liquid phase separation (LLPS) is quite important given the many numbers of diverse biomolecular systems undergoing this phenomenon. Regardless of the diversity, the processes underlying the formation of condensates exhibit physical similarities. Many studies have focused on condensates of long polymers, but very few systems of short polymer condensates have been observed and yet studied. Here we study a short polymer system of various lengths of poly-Adenine RNA and peptide formed by the RGRGG sequence repeats to understand the underlying thermodynamics of LLPS. We carried out MD simulations using the recently developed COCOMO coarse-grained (CG) model which revealed the possibility of condensates for lengths as short as 5-10 residues, which was then confirmed by experiment, making this one of the smallest LLPS systems yet observed. Condensation depends on polymer length and concentration, and phase boundaries were identified. A free energy model was also developed. Results show that the length dependent condensation is driven solely by entropy of confinement and identifies a negative free energy (-ΔG) of phase separation, indicating the stability of the condensates. The simplicity of this system will provide the basis for understanding more biologically realistic systems.

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Transient protein–protein interactions occur frequently under the crowded conditions encountered in biological environments. Tryptophan–cysteine quenching is introduced as an experimental approach with minimal labeling for characterizing such interactions between proteins due to its sensitivity to nano- to microsecond dynamics on subnanometer length scales. The experiments are paired with computational modeling at different resolutions including fully atomistic molecular dynamics simulations for interpretation of the experimental observables and to gain molecular-level insights. This approach is applied to model systems, villin variants and the drkN SH3 domain, in the presence of protein G crowders. It is demonstrated that Trp-Cys quenching experiments can differentiate between overall attractive and repulsive interactions between different proteins, and they can discern variations in interaction preferences at different protein surface locations. The close integration between experiment and simulations also provides an opportunity to evaluate different molecular force fields for the simulation of concentrated protein solutions.