Hydrogen Treatment for Superparamagnetic VO2 Nanowires with Large Room-Temperature Magnetoresistance.

One ‐ dimensional (1D) transition metal oxide (TMO) nanostructures are actively pursued in spintronic devices owing to their nontrivial d electron magnetism and confined electron transport pathways. However, for TMOs, the realization of 1D structures with long ‐ range magnetic order to achieve a sensitive magnetoelectric response near room temperature has been a longstanding challenge. Herein, we exploit a chemical hydric effect to regulate the spin structure of 1D V – V atomic chains in monoclinic VO2 nanowires. Hydrogen treatment introduced V3+ (3d2) ions into the 1D zigzag V – V chains, triggering the formation of ferromagnetically coupled V3+ – V4+ dimers to produce 1D superparamagnetic chains and achieve large room ‐ temperature negative magnetoresistance (−23.9 %, 300 K, 0.5 T). This approach offers new opportunities to regulate the spin structure of 1D nanostructures to control the intrinsic magnetoelectric properties of spintronic materials. Die Spinstruktur der eindimensionalen V ‐ V ‐ Ketten in monoklinen VO2 ‐ Nanodrähten wurde durch Wasserstoffbehandlung modifiziert, wodurch V3+ ‐ Ionen und ferromagnetisch gekoppelte V3+ ‐ V4+ ‐ Dimere in den Ketten erzeugt wurden. Die neue Struktur besteht aus superparamagnetischen Ketten und zeichnet sich durch einen großen negativen Magnetwiderstand bei Raumtemperatur aus. [ABSTRACT FROM AUTHOR]