# Impact of Stoichiometry of Yb2Ti2O7 on its Physical Properties

## TL;DR

This study investigates how off-stoichiometry affects the structure, magnetic properties, and heat capacity of Yb2Ti2O7, demonstrating the importance of precise stoichiometry and introducing a method for high-quality crystal growth.

## Contribution

It provides new insights into the effects of doping on Yb2Ti2O7's physical properties and presents a refined crystal growth technique for high-quality samples.

## Key findings

- Positive doping increases lattice parameter and decreases Curie-Weiss temperature.
- Doped samples show suppressed heat capacity peaks and altered entropy recovery.
- Traditional growth methods may produce off-stoichiometric crystals.

## Abstract

A series of Yb2Ti2O7 doped samples demonstrates the effects of off-stoichiometry on Yb2Ti2O7's structure, properties, and magnetic ground state via x-ray diffraction, specific heat, and magnetization measurements. A stoichiometric single crystal of Yb2Ti2O7 grown by the traveling solvent floating zone technique (solvent = 30 wt% rutile TiO2 and 70 wt% Yb2Ti2O7) is characterized and evaluated in light of this series. Our data shows that upon positive x doping, the cubic lattice parameter a increases and the Curie-Weiss temperature decreases. Heat capacity measurements of stoichiometric Yb2Ti2O7 samples exhibit a sharp, first-order peak at T = 268(4) mK that is suppressed in magnitude and temperature in samples doped off ideal stoichiometry. The full entropy recovered per Yb ion is 5.7 J/K ~ Rln2. Our work establishes the effects of doping on Yb2Ti2O7's physical properties, which provides further evidence indicating that previous crystals grown by the traditional floating zone method are doped off ideal stoichiometry. Additionally, we present how to grow high-quality colorless single crystals of Yb2Ti2O7 by the traveling solvent floating zone growth method.