Curvature-engineered magnetism and interfacial charge transfer in 1D CrCl3@MWCNTs heterostructures.

Curvature-induced magnetic and electronic modulation in curved van der Waals magnets under one-dimensional confinement can generate novel quantum properties that make them highly promising for next-generation nanoscale spintronic applications. Here, a template-assisted growth method is reported for highly crystalline single-walled CrCl3 nanotubes ranging from approximately 2.5 to 7 nm within the internal cavities of multi-walled carbon nanotubes (MWCNTs). Atomic-scale structural measurements and elemental mapping are performed using aberration-corrected transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) to confirm the presence of CrCl3 nanotubes. 4D-STEM is used to analyze the electronic behavior of the synthesized 1D CrCl3@MWCNT heterostructure. Magnetic properties are examined through X-ray magnetic circular dichroism (XMCD) and SQUID magnetometry. The results show that quantum confinement effects, curvature-induced strain, and interface-driven charge transfer between MWCNTs and CrCl3 tubes disturb the local Cr3+ environment, leading to curvature-stabilized, field-induced magnetism under an external magnetic field. Our findings offer insights into the interactions of encapsulated single-walled CrCl3 spins within MWCNTs, highlighting their potential as a platform for electrical spin modulation and interfacial engineering at the nanoscale in one-dimensional magnetic systems.