Strain-Assembled Crystalline SrRuO₃ Microtube and Emergent Curvilinear Magnetism

Strain-induced self-assembly presents a promising avenue for constructing novel microstructures, which can be used to simulate natural creatures and fabricate complex devices. In this work, with crystalline ferromagnetic metallic SrRuO₃ nanomembrane as a model system, we successfully realize the fabrication of micro-scale magnetic tubular structures. By utilizing the in-plane anisotropic lattice strain in SrTiO₃/SrRuO₃ bilayer grown on SrTiO₃ (110) substrate, we demonstrate the precise control of orientation and diameter of resulting microtubes. More interesting is that the artificially fabricated microtubes exhibit radial curvilinear magnetism due to the spin-orbit coupling induced perpendicular magnetic anisotropy in SrRuO₃ nanomembrane. This was confirmed by macroscopic magnetization measurement, which revealed the continuously-rotated magnetic moment along the radial direction. Moreover, the magnetoelectronic transport measurement on a single microtube reveals that the overall magnetoresistance is closely related to the local magnetic moment distribution in the curved structure. This behavior can be modeled by integrating the magnetoresistance contributions from all longitudinal strips of the radial-magnetized microtube. Our findings not only advance the understanding of magnetoelectric effects in curvilinear magnetism but also provide valuable insight and guidance in designing innovative spintronic devices.