Doping-induced quantum cross-over in Er$_2$Ti$_{2-x}$Sn$_x$O$_7$

TL;DR

This study investigates how doping affects the magnetic properties of Er$_2$Ti$_{2-x}$Sn$_x$O$_7$, revealing a doping-induced quantum phase transition and long-range magnetic order at high doping levels.

Contribution

It provides the first evidence of long-range order in Er$_2$Sn$_2$O$_7$ and discusses a possible quantum phase transition near a specific doping level.

Findings

Linear decrease of ordering temperature with doping for small x

Emergence of new magnetic Bragg peaks around x=1.7

Long-range magnetic order observed in Er$_2$Sn$_2$O$_7$ at 130 mK

Abstract

We present the results of the investigation of magnetic properties of the Er$_2$Ti$_{2-x}$Sn$_x$O$_7$ series. For small doping values the ordering temperature decreases linearly with $x$ while the moment configuration remains the same as in the $x = 0$ parent compound. Around $x = 1.7$ doping level we observe a change in the behavior, where the ordering temperature starts to increase and new magnetic Bragg peaks appear. For the first time we present evidence of a long-range order (LRO) in Er$_2$Sn$_2$O$_7$ ($x = 2.0$) below $T_N = 130$ mK. It is revealed that the moment configuration corresponds to a Palmer-Chalker type with a value of the magnetic moment significantly renormalized compared to $x = 0$. We discuss our results in the framework of a possible quantum phase transition occurring close to $x = 1.7$.