Meissner to ferromagnetic phase transition in La-decorated functionalized Nb₂C MXene: an experimental and...

This work reports experimental and computational magnetic phase transition from superconducting-diamagnet to ferromagnet in lanthanum (La)-doped functionalized Nb₂C MXene. Co-precipitation method is used to synthesize La-doped Nb₂C MXene. Structure and morphology of the compound are studied through x-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and energy dispersion spectroscopy, confirming the successful doping of La while retaining the two-dimensional (2D) structure of MXene. The magnetic properties of doped sample are studied using field-cooled and zero-field-cooled curves as well as from magnetization (M) versus applied magnetic field (H) graphs. Contrary to the superconductivity-like diamagnetic behavior in pristine Nb₂C MXene, the La-doped MXene converts the diamagnetism into the ferromagnetic (FM) phases at all temperatures. The ferromagnetism arises due to the pinning of magnetic spins pinned by Lanthanum itself. The computational analysis of pristine Nb₂C MXene confirms its diamagnetic behavior and further clarifies the role of La and functional groups (O and F) in the reduction of diamagnetic behavior in La-doped Nb₂C MXene while inducing FM nature. This work provides an interesting superconducting-diamagnetic to FM transition with a possibility of its implementation in 2D spintronics.