Yb$_{2}$Pt$_{2}$Pb: Magnetic frustration in the Shastry-Sutherland lattice

TL;DR

This study reports the synthesis and characterization of Yb$_{2}$Pt$_{2}$Pb, revealing magnetic frustration in a layered structure with a Shastry-Sutherland lattice, leading to complex magnetic behavior and a low antiferromagnetic transition temperature.

Contribution

First experimental investigation of Yb$_{2}$Pt$_{2}$Pb showing magnetic frustration and quasi-two-dimensional magnetic properties in a Shastry-Sutherland lattice system.

Findings

Yb ions are trivalent with a well-isolated doublet ground state.

Strong magnetic anisotropy observed with susceptibility ratio up to 30.

Antiferromagnetic order at T_N=2.07 K with evidence of magnetic frustration.

Abstract

We have synthesized single crystals of Yb$_{2}$Pt$_{2}$Pb, which crystallize in the layered U$_{2}$Pt$_{2}$Sn-type structure, where planes of Yb ions lie on a triangular network. We report here the first results of magnetization, specific heat, and electrical resistivity experiments. The lattice constants and high temperature magnetic susceptibility indicate that the Yb ions are trivalent, while Schottky peaks in the specific heat show that the ground state is a well isolated doublet. Significant magnetic anisotropy is observed, with the ratio of susceptibilities perpendicular and parallel to the magnetic planes differing by as much as a factor of 30 at the lowest temperatures. Antiferromagnetic order occurs at a N\'eel temperature $T_{\rm N}$=2.07 K, a transition temperature which is more than an order of magnitude smaller than the mean field interactions reflected by the in-plane Weiss temperature. Further evidence for short ranged magnetic fluctuations is found in the magnetic susceptibility and electrical resistivity, which have broad peaks above $T_{\rm N}$, and in the slow development of the magnetic entropy at $T_{\rm N}$. Our experiments indicate that Yb$_{2}$Pt$_{2}$Pb is a quasi-two dimensional and localized moment system, where strong magnetic frustration may arise from the geometry of the underlying Shastry-Sutherland lattice.