Crystal field states in a Quantum Spin Ice]{Crystal field states of Pr$^{3+}$ in the candidate quantum spin ice Pr$_{2}$Sn$_{2}$O$_{7}$

TL;DR

This study uses neutron spectroscopy to analyze the crystal-field states of Pr$^{3+}$ in Pr$_{2}$Sn$_{2}$O$_{7}$, revealing a non-Kramers doublet with Ising anisotropy suitable for quantum spin ice behavior.

Contribution

The paper provides detailed crystal field parameters and identifies the ground state as a non-Kramers doublet with significant quantum fluctuations in Pr$_{2}$Sn$_{2}$O$_{7}.

Findings

Ground state is a non-Kramers doublet with Ising anisotropy.

Significant admixture of states suggests quantum zero-point fluctuations.

Material exhibits properties consistent with quantum spin ice.

Abstract

Neutron time-of-flight spectroscopy has been employed to study the crystal-field splitting of Pr$^{3+}$ in the pyrochlore stannate Pr$_{2}$Sn$_{2}$O$_{7}$. The crystal field has been parameterized from a profile fit to the observed neutron spectrum. The single-ion ground state is a well isolated non-Kramers doublet of $\Gamma_3^+$ symmetry with a large Ising-like anisotropy, $\chi_{zz} /\chi_\perp \approx 60$ at 10 K, but with a significant admixture of terms $| M_J \neq \pm J >$ which can give rise to quantum zero-point fluctuations. This magnetic state satisfies the requirements for quantum spin ice behavior.