摘要：By applying density functional theory calculations to iron chalcogenides, we find that magnetic order in Fe1+ y Te and magnetic instability at ( π , π ) in K y Fe2Se2 are controlled by interstitial and interlayer cations, respectively. While in Fe1+ y Te, magnetic phase transitions occur among collinear, exotic bicollinear and plaquette-ordered antiferronmagnetic states when the height of interstitial irons measured from iron plane or the concentration of interstitial irons is varied, the magnetic instability at ( π , π ) which is believed to be responsible for the Cooper pairing in iron pnictides is significantly enhanced when y is much smaller than 1 in K y Fe2Se2. Our results indicate that, similar to iron pnictides, itinerant electrons play important roles in iron chalcogenides, even though the fluctuating local moments become larger.
