Interactions of Topological (Crystalline) Insulators with Superconductivity and Magnetism T. Valla Brookhaven National Laboratory, Upton, USA Topological insulators (TI) are a new class of insulators with the inverted bulk gap due to strong spin-orbit coupling. On their interfaces with ordinary insulators, gapless states inevitably occur. 3D TIs have surface states (SS) with an odd number of massless Dirac cones with the spin-momentum locked electrons. In related topological crystalline insulators (TCI), the existence and protection of SS is dictated by symmetries of the underlying lattice. The physics of these materials is even more interesting with the inclusion of correlations: when interacting with magnetism or superconductivity, TIs and TCIs are predicted to show a variety of highly unusual phenomena, ranging from induced magnetic monopoles, quantum anomalous Hall effect, p+ip superconducting order parameter, Majorana and Weyl fermions, etc. Some of these exotic phenomena might be used for spintronics applications, magnetic recording and quantum computing, but problems with materials and very stringent constraints on physical parameters render the wide-spread applications extremely difficult. Therefore, both the materials synthesis and the physical parameters constraints have to be explored and optimized. Here, we present the angle and spin resolved photoemission spectroscopy studies of various in-situ grown TI and TCI hetero-structures involving interfaces with magnetic and superconducting materials in a wide range of thicknesses and compositions of building blocks. We discuss the observed features in the low-energy electronic spectra and relate them to the relevant macroscopic properties.