Unstable Shastry-Sutherland phase in Ce2Pd2Sn

Abstract

Thermal (CP), magnetic (M and χac), and transport (ρ) measurements on Ce2Pd2Sn are reported. High-temperature properties are well described by the presence of two excited crystal-field levels at (65±5) K and (230±20) K, with negligible hybridization (Kondo) effects. According to literature, two transitions were observed at TM=4.8 K and TC=2.1 K, respectively. The upper transition cannot be considered as a standard antiferromagnetic because of frustration effects in a triangular network of Ce atoms and the positive sign of the paramagnetic temperature θLTP=4.4 K. The nature of the intermediated phase is described accounting for the formation of ferromagnetic (F) Ce dimers disposed in a quasi-two-dimensional square lattice, resembling a Shastry-Sutherland pattern. According to hysteretic features in ρ(T) and χac(T), the lower F transition is of first order, with CP (T<TC) revealing a gap of anisotropy Eg≈7 K.