Magnetic phase transition from paramagnetic in Nb2AlC-MAX to superconductivity-like diamagnetic in Nb2C-MXene: an experimental and computational analysis.
Royal Society of Chemistry (RSC)
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Din Babar, Z. U., Fatheema, J., Arif, N., Anwar, M., Gul, S., Iqbal, M., & Rizwan, S. (2020). Magnetic phase transition from paramagnetic in Nb2AlC-MAX to superconductivity-like diamagnetic in Nb2C-MXene: an experimental and computational analysis.. RSC Adv, 10 (43), 25669-25678. https://doi.org/10.1039/d0ra04568c
Funder: National University of Sciences and Technology
Transition metal carbides (TMCs) have recently emerged as competent members among the family of two-dimensional (2D) materials, owing to their promising applications. There are many promising applications of MXenes; however, their magnetic properties lack a wide margin, both experimentally as well as theoretically, which needs to be investigated for potential use in spintronics. In this study, we carried out a comprehensive etching process via selective extraction of Al layers from Nb2AlC-MAX using a wet electrochemical route under well-optimized conditions to obtain fine 2D-Nb2C MXene sheets. Structural analysis using X-ray diffraction (XRD) confirms the effective removal of Al followed by confirmation of a 2D layered structure from morphological analysis using scanning electron microscopy (SEM). Zero-field-cooled (ZFC) and field-cooled (FC) measurements of MAX and MXene at different field strengths were performed using a superconducting quantum interference device (SQUID). Magnetic measurements reveal the paramagnetic nature of Nb2AlC-MAX measured under 5 mT; however, this changes to a clear superconductor-like diamagnetic behavior with a shift of the magnetization from positive to negative values at low temperatures when measured under 5 mT and 10 mT for Nb2C MXene. The diamagnetism, however, is changed to paramagnetism at 100 mT, which shows the existence of critical fields known typically for a type-II superconductor. To gain an insight into this unusual behavior in MXene, density functional theory (DFT) first-principles calculation was also performed in Wein2K software using spin-polarized generalized gradient approximation (sp-GGA). The magnetic moment of the compound is calculated to be negative, which corresponds well with the experimental finding and suggests that the negative magnetic moment originated from the d-orbital of Nb2C. The present report provides a pathway to deeply understanding the existence of superconductivity-like diamagnetic behavior in Nb2C MXene, which is useful for future magnetic applications.
United States Agency for International Development (783)
Higher Education Commission, Pakistan (6040)
External DOI: https://doi.org/10.1039/d0ra04568c
This record's URL: https://www.repository.cam.ac.uk/handle/1810/337843
Attribution 4.0 International
Licence URL: https://creativecommons.org/licenses/by/4.0/