Magnetic phase diagram of PrCo2Si2 with long period commensurate structure

The electrical resistivity of PrCo2Si2 with a long-period commensurate spin structure has been measured in a magnetic field up to 9 Tesla, together wi th the heat capacity up to 5 Tesla. The resistivity changes drastically wit h step-like jumps at the successive transition points accompanying the chan ge of the antiferromagnetic propagation vectors. From the resistivity measu rements, four distinct phases are confirmed below the antiferromagnetic tra nsition temperature. A temperature-magnetic field phase diagram of PrCo2Si2 is presented.