Abstract: The discovery of superconductivity with a critical temperature (Tc) higher than 40 K in the iron arsenide Ln(O,F)FeAs has drawn much interest in condensed matter physics. Later discoveries, including the enhancement of Tc up to 55 K, has evoked intense excitement in the pilgrimage towards the understanding of the mechanism of high Tc superconductivity, while providing a brand new family of materials to address this issue. In this review we present our group's major research on new iron based superconductors, including: (1) our initial investigations; (2) the synthesis of iron arsenide single crystals and the characterization of its physical properties; (3) the electronic phase diagram of iron based superconductors and the coexistence between spin density waves and superconductivity; (4) the effect of isotope exchange on spin density waves and superconducting transitions. To finish, we propose possible future directions in this field.