Mapping the first order magnetic transition in Yb$_2$Ti$_2$O$_7$

TL;DR

This study identifies a first-order ferromagnetic transition in Yb$_2$Ti$_2$O$_7$ at very low temperatures, clarifying its complex magnetic ground state and the role of fluctuations and slow dynamics.

Contribution

It provides detailed magnetization measurements revealing a first-order transition, contributing new insights into the magnetic phase behavior of Yb$_2$Ti$_2$O$_7$.

Findings

First-order ferromagnetic transition at 245 mK and 150 mK

Transition persists under magnetic fields up to ~200 Oe

Presence of residual fluctuations and slow dynamics

Abstract

The very nature of the ground state of the pyrochlore compound Yb$_2$Ti$_2$O$_7$ is much debated, as experimental results demonstrate evidence for both a disordered or a long-range ordered ground state. Indeed, the delicate balance of exchange interactions and anisotropy is believed to lead to competing states, such as a Quantum Spin Liquid state or a ferromagnetic state which may originate from an Anderson-Higgs transition. We present a detailed magnetization study demonstrating a first order ferromagnetic transition at 245 mK and 150 mK in a powder and a single crystal sample respectively. Its first-order character is preserved up to applied fields of $\sim$ 200 Oe. The transition stabilizes a ferromagnetic component and involves slow dynamics in the magnetization. Residual fluctuations are also evidenced, the presence of which might explain some of the discrepancies between previously published data for Yb$_2$Ti$_2$O$_7$.