Angle-resolved photoemission spectroscopy (ARPES) has become a widely used technique nowadays in the process of understanding the physics of exotic systems like the high-T_c superconductors, the Topological systems and the recently emerging Weyl semimetals, because of its ability of directly probing the low-energy band structure with ultra-high energy resolution, Fermi surface topology, orbital symmetry and importantly the electronic correlations. Partly, the success of ARPES technique also comes from the direct comparison between the experimental data and that of well-established density functional theory (DFT) calculations. Because of this reason, ARPES also has become a favorite experimental tool for the DFT community to test their theoretical findings. High-T_c superconductivity and Topological systems are two major subjects that are hugely benefitted in the last two decades with the advent of ARPES technique. In this talk, I primarily concentrate discussing the working principles of ARPES technique and our ARPES studies on ironpnictide superconductors [1] performed to understand the mechanism of superconductivity. If the time permits, I will also show our recent studies on the Topological superconductor (BiPd), performed in search of the topological Dirac states and the Majorana fermions [2].

1.  S. Thirupathaiah et al., PRB 93, 205143 (2016);  PRB 88, 140505(R) (2013);  PRB 86, 214508 (2012);  PRB 84, 014531(2011);  PRB 81, 104512 (2010).  

2.  S. Thirupathaiah et al., PRL 117, 177001(2016).