Field induced spin freezing and low temperature heat capacity of disordered pyrochlore oxide Ho$_{2}$Zr$_{2}$O$_{7}$

TL;DR

This study investigates how chemical disorder in Ho$_{2}$Zr$_{2}$O$_{7}$ affects its magnetic properties and spin freezing behavior, contrasting it with the well-known spin ice Ho$_{2}$Ti$_{2}$O$_{7}$, revealing suppression of spin ice characteristics due to structural disorder.

Contribution

It provides detailed experimental insights into how structural disorder influences spin dynamics and frustration in a disordered pyrochlore, expanding understanding of spin ice suppression mechanisms.

Findings

Ho$_{2}$Zr$_{2}$O$_{7}$ remains dynamic down to 30 mK without residual entropy.

Magnetic susceptibility is large and field-dependent, indicating suppressed spin ice behavior.

Freezing transition occurs around 10 K at 10 kOe, showing field-induced spin freezing.

Abstract

Spin ice materials are the model systems that have a zero-point entropy as \textit{T} $\rightarrow$ 0 K, owing to the frozen disordered states. Here, we chemically alter the well-known spin ice Ho$_{2}$Ti$_{2}$O$_{7}$ by replacing Ti sites with isovalent but larger Zr ion. Unlike the Ho$_{2}$Ti$_{2}$O$_{7}$ which is a pyrochlore material, Ho$_{2}$Zr$_{2}$O$_{7}$ crystallizes in disordered pyrochlore structure. We have performed detailed structural, ac magnetic susceptibility and heat capacity studies on Ho$_{2}$Zr$_{2}$O$_{7}$ to investigate the interplay of structural disorder and frustrated interactions. The zero-field ground state exhibits large magnetic susceptibility and remains dynamic down to 30 mK without showing Pauling's residual entropy. The dynamic state is suppressed continuously with the magnetic field and freezing transition evolves ($\sim$ 10 K) at a field of $\sim$ 10 kOe. These results suggest that the alteration of chemical order and local strain in Ho$_{2}$Ti$_{2}$O$_{7}$ prevents the development of spin ice state and provides a new material to study the geometrical frustration based on the structure.