Microwave surface impedance measurements of LiFeAs, LiFe(As,P) and FeSe1−xTex single crystals

► We measured microwave surface impedances of 3 kinds of Fe-based superconductors. ► LiFeAs and LiFe(As,P) has plural superconducting gaps without any nodes. ► The Quadratic temperature dependence of penetration depth appears in FeSe1-x Tex. ► This behavior of FeSe1-x Tex indicates the existence of quasiparticle excitations. ► Real parts of the microwave conductivity exhibit a large enhancement below Tc.