Coexistence of ferromagnetism and superconductivity in MWCNT/Bi2SiO5 nanocomposites

Abstract

This work explores the temperature and field-dependent magnetic properties of Bi2SiO5 (BSO)/multiwall carbon nanotube (MWCNT) nanocomposites prepared by hydrothermal method using different content of magnetic MWCNT (from 1 to 20 wt%). A pure BSO prepared by the same method was also studied as a reference. Phase purity and structure of the pure BSO and CBSO nanocomposites were analyzed by employing the Rietveld refinement of an X-ray diffraction pattern. DC magnetization analysis confirms the co-existence of multiple magnetic phases in CBSO nanocomposites, where a paramagnetic (PM) to ferromagnetic (FM) transition experiences at ∼33 K, and a cluster spin glass behavior at near Curie temperature (i.e., TC ∼25 K). A weak superconducting transition (TSC) at around ∼23 K was observed for all the CBSO nanocomposite samples (i.e., 2.5 wt% MWCNT and above samples). Moreover, a novel feature of these nanocomposites is that they exhibit a complex magnetism corresponding to the co-existence of ferromagnetism and superconductivity. This behavior can be exploited to engineer a magnetic CBSO composites system with the magnetic transition tune by compositional structure, with interesting potential applications.