Recently, the team of Hariom Jani from the University of Oxford and the team of Junxiong Hu from the National University of Singapore (NU) in the international top journal Nature Materials (IF:412) Combining the antiferromagnetic layer with the adipose bent nanostructure can realize the spin texture design through magnetoelastic geometry in quasi-static and dynamic states, thus opening up a new field of exploration for curvilinear antiferromagnetism and unconventional computing.
Antiferromagnets carrying real-space topologies are promising platforms for simulating fundamental ultrafast phenomena and exploring spintronics. However, they can only be epitaxial fabricated on a specific symmetrically matched substrate, thus maintaining their inherent magnetocrystalline order. Thislimits their binding to different carriers, limiting the scope of basic and applied research. In the authors' study, they overcame this limitation by designing separable -Fe2O3 crystal antiferromagnetic nanofilms. Firstly, the transport-based antiferromagnetic vector mapping shows that planar nanofilms have spin-directed transitions and abundant topological phenomena. Second, extreme flexibility is utilized to demonstrate the reconfiguration of the antiferromagnetic state of the three-dimensional membrane fold caused by flexure-induced strain. Finally, they combined these research results to achieve a strain-driven, non-thermally generated topological texture at room temperature using a controllable robotic arm. This integration of independent antiferromagnetic layers and planar bent nanostructures can realize spin texture design through magnetoelastic geometric effects in quasi-static and dynamic states, opening up new explorations for curvilinear antiferromagnetism and unconventional computations.
Design and fabrication of membranes
Firstly, the authors used selective water etching technology to prepare (001)-oriented, rhodium-doped -Fe2O3 independent films on the epitaxial heterostructures grown by pulsed laser deposition. 
Fig.1 Membrane design and characterizationThe quality of the -Fe2O3 layer depends mainly on the choice of substrate and intermediate (buffer) layer to reduce lattice mismatch between layers. Due to the trigonal symmetry of -Fe2O3, they chose single crystal (001)oriented -Al2O3 and (111)oriented SRTio3(STO) substrates as the growth template, and (111)oriented SR3Al2O6 (SAO) as the water-soluble sacrificial layer. Water etching of the SAO produces an independent oxide film that is transferred to the desired support by direct or indirect transfer (Figure 1A). The authors then diffracted electrons by X-ray diffraction and selective regionThe mass and orientation of the buffered -Fe2O3 crystal film were determined(Figure 1c-f). The addition of a buffer layer results in a larger crack-free area for the stand-alone AFM membrane compared to the unbuffered AFM membrane (Figure 1B). The former involves shoveling the floating membrane directly onto the support, while the latter requires a temporary organic support to be spun in place prior to final transfer. Throughout their work, they used both methods in different experiments.
Magnetic transitions in membranes
Reliable topological texture generation in Fe2O3 requires the presence of a spin-heavy orientation (morin) phase transition, which mimics the Kibble-Zurek phenomenon. At the Morin transition temperature, the anisotropy undergoes a sign inversion from the easy axis (k>0) to the easy plane (k<0), resulting in the spin flipping from an out-of-plane (OOP) to an in-plane (IP) configuration. Superconducting quantum interferometry (QTP) magnetometry and X-ray spectroscopy confirm the presence of a sharp morin transition near room temperature. This is in contrast to chemically exfoliated hemochromatic membranes, in which the matopelin transition is completely inhibited due to altered magnetocrystalline interactions. They found that the transition of the separating membrane was similar in quality to that of the attached epitaxial film (although the former was more defective than the latter), but the transition of buffer-Fe2O3 was more pronounced. The authors conclude that the experimental water-etched film is a good independent platform for finding the real-space topological AFM order.
Atomic force microscopy ordered nanoscale mapping
To image local AFM textures, authorsSTXM experiments were performed in X-ray magnetic linear dichroism (XMLD) mode(An element-specific spectral microscopy technique with a large depth of focus that allows for unambiguous identification of AFM contrast). 
Fig.2 Morin transition and topological AFM texture generationA beam of FEL3 edge X-rays is focused onto the AFM membrane at normal incidence, and changes in absorption are monitored for transmission through a spot detector (Figure 2A). In this geometry, the X-ray polarization (linear level (LH)) of the -Fe2O3 film is located on the base plane, and the IP and OOP AFM orientations are clearly distinguished because they provide different XMLD signals. In addition, changing the sample azimuth by using an in-situ rotating platform or X-ray polarization, the authorsThe relative orientation of the X-ray polarization and the IP Neel sequence is changed, resulting in an ordered nanoscale reconstruction of the AFM.
Bend-driven state reconstruction across 3D folds
To investigate the effects of deflection, the authors then imaged the natural deflection regions in the membrane folds that occur incidentally during the metastasis. The shape was confirmed by a confocal microscope, which plotted the height profile of the membrane (Figure 3B). 
Fig.3 Bend-driven AFM state space reconstructionIn addition, the slope of the curved region appears darker in the STXM image (Figure 3C) due to the exponential attenuation of the signal with the thickness of the valid sample. The author found thatBuffered -Fe2O3 films are not as brittle as ceramic-based oxides, but are very flexible and can form "folds". Figure 3 shows that the maximum curvature of the pleat is 00003nm-1。In extreme cases, they can even observe a "folded" membrane at a full 180°. In addition, the large buffer film (type C) can maintain a complex strain distribution without breakage.
Strain and anisotropy models
The authors numerically calculated the strain distribution on the folds by using a finite element mechanical model of the buffer membrane, which is very close to the contour determined by confocal microscopy. It was found that the deflection resulted in considerable uniaxial IP tensile and compressive strain, distributed along the thickness of the film (Z-direction) such that the neutral (unstrained) line was located near the middle of the buffer membrane. Due to the presence of the buffer layer, the buffer layer itself can accommodate a certain amount of strain, so the average net strain on the -Fe2O3 layer is actually non-zero. 
Fig.4. Bending strain and anisotropy modelIn addition, the strength of the average net strain varies gradually along the length of the foldChange the symbol near the point where the curvature is zero(Figure 4a). Finally, for this model**, the inverted buffer membrane should invert the strain distribution sign (Figure 4b). Then, to base this observation on a more quantitative basis, the authors calculated the local TM by combining the thickness average strain curve of the mechanical model with the strain dependence of the TM determined in the literature (Fig. 4C). It should be noted thatThe strain in other work is substrate-induced and biaxial, whereas here the bending-induced strain is predominantly uniaxial. In the buffer membrane with the -Fe2O3 side facing up, the authors also found:The net compressive strain at the bottom of the fold and the net tensile strain at the peak should result in a local tmIncrease and decrease by about 10% respectively. Overall, the AFM state reconstruction model is consistent with the experimental results determined by the STXM images taken across the folds.
Non-thermal topological texture by strain
The authors also deployed a gas cell manipulator (Fig. 5A, B), where changes in gas pressure inside the cell bent the silicon nitride scaffold, resulting in controlled in-situ stretching of the AFM membrane. 
Fig.5. In-situ strain tuning of the AFM state and non-thermal generation of topologyThe properties of the flat membrane attached to the square support were explored and it was found that bending the scaffold creates a biaxial strain, the value of which can be precisely determined by measuring the deflection of the membrane by a change in the focus position of the microscope. But the geometry of this structureThis ensures that the strain is purely stretched in the center of the square, regardless of the presence or location of the buffer layer. At room temperature, without any strain, the sample is in the OOP state (tm; Figure 5c). Since the tensile strain inhibits the magnetic anisotropy, the pressure on the unit cell leads to the gradual increase of the IP domain. At higher gas pressures, the membrane transitions to an IP state with several small OOP plaques, very similar to the state at high temperatures and zero strain. Finally, we reconstructed the Neel vector map on the strain membrane to reveal the local IP changes in the spin texture. It is now possible to confirm the existence of a family of topological AFM textures with nontrivial entanglements, including (anti)mesons and dimesons (Figure 5D).
Conclusion
In this study, the authors demonstrated that the stand-alone -Fe2O3 membrane has a range of IP and OOP AFM states, including textures that are proven to be topological, using a powerful transport-based AFM vector mapping technique. The results suggest that the background AFM in which these textures occur can be modulated by bending-induced strain in three-dimensional folded structures. In addition, using the in-situ strain manipulator, the authors also demonstrated that non-thermal Kibble-Zurek generation of topological AFM states at room temperature can be achieved by using controllable structure tuning. At the fundamental level, the results show that strain modulation has the potential to design and manipulate topological AFM textures, adding a new magnetic topological prospect to the emerging research field of using quantum material films to generate singular states. The findings also pave the way for exploring static and dynamic AFM evolutions triggered by in-situ electrical, magnetic, optical, or structural perturbations. For example, the authors envision the control of electrical triggering topological reconfiguration and dynamics through local piezoelectricity. In addition, by integrating extremely flexible AFM ribbons onto well-designed three-dimensional nanostructures, it is possible to induce novel symmetry-disrupting exchanges or anisotropic interactions, e.g.,Through curvilinear geometry and magnetoelastic effects, it is possible to design spatially varying magnetic states or to achieve chiral textures that have not been discovered so far. In terms of applications, the development of substrate-free AFM films can maintain magnetocrystalline properties and topological order, addressing the main barriers that hinder the integration of crystalline AFM materials into established spintronics platforms. Specifically, complex and dense topological AFM structures are expected to have fast nonlinear dynamics, which can be turned onExplore AFM-based silicon-compatible ultrafast reservoir calculations or 3D compact AFM logical storage arrays. Hint:If there is any infringement, please contact me thank you! **10,000 Fans Incentive Plan