  In this paper, pressure effect on superconductivity and magnetism has been
investigated in FeSex (x = 0.80, 0.88). The magnetization curves display
anomaly at Ts1 106 K and Ts2 78 K except for the superconducting diamagnetic
transition around Tc 8 K. The magnetic anomaly at Ts1 and Ts2 can be related to
a ferromagnetic and an antiferromagnetic phase transition, respectively, as
revealed by specific heat measurements. The application of pressure not only
raises Tc, but also increases both Ts1 and Ts2. This system shows clear
evidence that superconductivity arises in a phase with strong magnetic
character and the superconductivity coexists with magnetism. In addition, the
specific heat anomaly associated with the superconducting transition seems to
be absent.
