Dilution effects in Ho$_{2-x}$Y$_x$Sn$_2$O$_7$: from the Spin Ice to the single-ion magnet

TL;DR

This study investigates how substituting Y for Ho in Ho$_{2-x}$Y$_x$Sn$_2$O$_7$ affects its magnetic properties, revealing weak effects on Spin Ice behavior at low doping and significant changes at high doping levels.

Contribution

It provides new insights into the evolution of magnetic dynamics and crystal field effects in Ho$_{2-x}$Y$_x$Sn$_2$O$_7$ across different doping levels.

Findings

Spin Ice ground state is weakly affected for x ≤ 0.3.

Low-temperature dynamics are modified by doping.

High doping leads to fluctuations among crystal field levels.

Abstract

A study of the modifications of the magnetic properties of Ho$_{2-x}$Y$_x$Sn$_2$O$_7$ upon varying the concentration of diamagnetic Y$^{3+}$ ions is presented. Magnetization and specific heat measurements show that the Spin Ice ground-state is only weakly affected by doping for $x\leq 0.3$, even if non-negligible changes in the crystal field at Ho$^{3+}$ occur. In this low doping range $\mu$SR relaxation measurements evidence a modification in the low-temperature dynamics with respect to the one observed in the pure Spin Ice. For $x\to 2$, or at high temperature, the dynamics involve fluctuations among Ho$^{3+}$ crystal field levels which give rise to a characteristic peak in $^{119}$Sn nuclear spin-lattice relaxation rate. In this doping limit also the changes in Ho$^{3+}$ magnetic moment suggest a variation of the crystal field parameters.