# Strain‐Assembled Crystalline SrRuO3 Microtube and Emergent Curvilinear Magnetism

## TL;DR

Scientists created magnetic microtubes using strain-induced self-assembly and found that their curved shape leads to unique magnetic properties.

## Contribution

A novel method for fabricating strain-assembled crystalline SrRuO3 microtubes with controllable orientation and diameter, revealing emergent curvilinear magnetism.

## Key findings

- Microtubes exhibit radial curvilinear magnetism due to spin-orbit coupling-induced perpendicular magnetic anisotropy.
- Magnetoresistance in microtubes is closely related to local magnetic moment distribution in the curved structure.
- Macroscopic magnetization measurements confirm continuously rotated magnetic moments along the radial direction.

## Abstract

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.

The interfacial‐strain assembly based on planar nanomembranes presents a promising approach for constructing novel magnetic microstructures. By employing the perpendicular magnetic anisotropic SrRuO3 freestanding nanomembrane as a model system, we exploit the interfacial strain effect within the crystalline SrTiO3/SrRuO3 bilayer, and successfully fabricate the micro‐scale tubular structures with controllable orientation and diameter. Based on this, the radial curvilinear magnetism in microtubular SrRuO3 was investigated.