Pressure-induced transition in a heavy fermion YbPd2Si2

We report the results of a room-temperature investigation of the thermoelectric and the dilatometric properties of a heavy fermion system YbPd2Si2 (itterbium–palladium–silicon, 1–2–2) at high pressure P up to 22 GPa; YbPd2Si2 is a less-studied representative of the RM2X2 family (R=Ce, Yb, U; M=transition metal; X=Si, Ge) with the tetragonal ThCr2Si2-type structure of the I4/mmm space group. Around P∼6±0.5 GPa, a phase transition in Yb–Pd–Si was registered by the drastic changes in the pressure dependencies of the electrical resistance R, the thermopower (Seebeck effect) S, a temperature difference along a sample ΔT, and a sample's thickness Δx (related to compressibility). Both a nature of the found phase transition and a presumable P–T phase diagram of YbPd2Si2 are discussed.