Unstable Shastry-Sutherland phase in Ce$_{2}$Pd$_{2}$Sn

TL;DR

This study investigates the complex magnetic phases of Ce$_{2}$Pd$_{2}$Sn, revealing a frustrated intermediate phase with a Shastry-Sutherland pattern and a first-order ferromagnetic transition, supported by thermal, magnetic, and transport measurements.

Contribution

It provides the first detailed characterization of the unstable Shastry-Sutherland phase in Ce$_{2}$Pd$_{2}$Sn, highlighting the role of frustration and ferromagnetic dimers in its magnetic behavior.

Findings

High temperature properties explained by crystal field levels at 65K and 230K.

Identification of a frustrated intermediate phase with a Shastry-Sutherland pattern.

Observation of a first-order ferromagnetic transition with an anisotropy gap of about 7K.

Abstract

Thermal ($C_P$), magnetic ($M$ and $\chi_{ac}$) and transport ($\rho$) measurements on Ce$_{2}$Pd$_{2}$Sn are reported. High temperature properties are well described by the presence of two excited crystal field levels at $(65\pm 5)$K and $(230\pm 20)$K, with negligible hybridization (Kondo) effects. According to literature, two transitions were observed at $T_M=4.8$K and $T_C =2.1$K respectively. The upper transition cannot be considered as a standard anti-ferromagnetic because of frustration effects in a triangular network of Ce-atoms and the positive sign of the paramagnetic temperature $\theta_P^{LT} = 4.4$K. The nature of the this intermediated phase is described accounting for the formation of ferromagnetic (F) Ce-dimers disposed in a quasi-2D square lattice, resembling a Shastry-Sutherland pattern. According to hysteretic features in $\rho(T)$ and $\chi_{ac}(T)$, the lower F-transition is of first order, with $C_P(T<T_C)$ revealing a gap of anisotropy $E_g\approx 7$K.