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We report crystal growth and below 2.5K superconductivity of Nb 0.25 Bi 2 Se 3 . These crystals are grown by self flux method. The X-ray diffraction (XRD) pattern of as grown crystal flake shows (00l) plane (c-orientation) growth. The Rietveld refinement of crushed crystal powder XRD (PXRD) pattern confirms the phase purity of the studied sample having R-3m space group of rhombohedral crystalline structure. The Raman spectrum of the studied Nb 0.25 Bi 2 Se 3 crystal distinctly shows three well defined vibrational modes in terms of A 1 1g , Eg 2 , A 2 1g at around 72, 129 and 173cm -1 , which are slightly shifted in comparison to pure Bi 2 Se 3 . Magnetization studies in terms of field cooled (FC) and Zero field cooled (ZFC) magnetic susceptibility measurements show the diamagnetic transition (T c onset ) of the compound at around 2.5K and near saturation of the same below around 2.1K. The isothernal magnetization (MH) being taken at 2K, revealed the lower critical field (H c1 ) of around 50Oe and the upper critical field (H c2 ) of 900Oe. It is clear the studied Nb 0.25 Bi 2 Se 3 is a bulk superconductor. The superconducting critical parameters thus calculated viz. the coherence length, upper and lower critical fields and superconducting transition temperature for as grown Nb 0.25 Bi 2 Se 3 single crystal are reported here.

We study the structural and bulk superconducting properties of self flux grown PdBi 2 Te 3 single crystal. Phase purity of as grown crystal is confirmed by Rietveld refinement of gently crushed powder XRD of the same. PdBi 2 Te 3 crystallizes in rhombohedral structure with R-3 m space group along with small impurity of Bi. Scanning Electron Microscopy (SEM) images showed layered structure and the elemental analysis by energy dispersive X Ray analysis (EDAX) done on same confirmed the stoichiometry to be near to PdBi 2 Te 3 . Characteristic vibrational modes viz. A 1 1g , Eg 2 , A 2 1g are clearly observed in Raman spectrum, and are slightly shifted from that as in case of Bi 2 Te 3 . Bulk superconductivity is confirmed by FC and ZFC magnetization measurements (M-T) exhibiting diamagnetic transition with T c onset at around 6K. M-H plots at different temperatures of 2K, 2.5K, 3K, 3.5K, 4K, 4.5K, 5K and 6K showed clear opening of the loop right up to 6K. Both M-T and M-H clearly establish the appearance of bulk type II superconductivity below 6K in studied PdBi 2 Te 3 . The lower critical field H c1 and upper critical field H c2 are at 180Oe at 4800Oe respectively at 2K for as grown PdBi 2 Te 3 crystal. Other critical parameters of superconductivity such as coherence length, penetration depth and kappa parameter are also calculated.

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Superconductivity in topological materials has drawn a significant interest of the scientific community as these materials provide a hint of existence of Majorana fermions conceived from the quantized thermal conductivity, a zero-biased conduction peak and the anomalous Josephson effect. In this review, we make a systematic study of recent advances in the field of topological superconductivity. The article comprises of both bulk systems as well as heterostructures. A brief description of Majorana fermions and their relationship with topological superconductors and heterostructures is also carried out. Also, this review consists of details of key experimental techniques to characterize candidates of topological superconductivity. Moreover, we summarize the potential material candidate that may demonstrate topological superconductivity. We also consider some intrinsic odd-parity superconductors, non-centrosymmetric, centrosymmetric superconductors, doped topological insulators, doped topological crystalline insulators and some other materials that are expected to show superconductivity along with topological non-trivial states in bulk from. The effect of pressure, emergence of superconductivity in topological materials and Muon Spin Rotation (SR) studies are also summarized in this article.

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Materials exhibiting bulk superconductivity along with magnetoresistance (MR) in their normal state have emerged as suitable candidates for topological superconductivity. In this article, we report a flux free method to synthesize single crystal of topological superconductor candidate Sn4Au. The phase purity and single crystalline nature are confirmed through various characterizations viz. X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), selected Area electron diffraction (SAED), and transmission electron microscopy (TEM). Chemical states of the constituent element viz. Sn and Au are analyzed through X-Ray photoelectron spectroscopy (XPS). Superconductivity in synthesized Sn4Au single crystal is evident form -T plot and critical field (Hc) is determined through -H plot at 2K i.e., just below critical temperature Tc. A positive magnetoresistance (MR) is observed in -H measurements at different temperatures above Tc, viz. at 3K, 5K, 10K and 20K. Further, the magnetoconductivity (MC) is analyzed by using Hikami-Larkin-Nagaoka (HLN) formalism, which signifies the presence of weak antilocalization (WAL) effect in Sn4Au. Angle dependent magneto-transport measurement has been performed to detect the origin of observed WAL effect in Sn4Au single crystal. Normalized MC vs Hcosplot shows presence of topological surface states (TSS) in the studied system. It is evident that Sn4Au is a 2.6K topological superconductor.

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