Evidence for spin-glass ground state in fluorite-defect Er2Zr2O7 single crystals

We present the preparation and characterization of an $\mathrm{E}{\mathrm{r}}_{2}\mathrm{Z}{\mathrm{r}}_{2}{\mathrm{O}}_{7}$ single crystal. The material was studied by means of x-ray and neutron diffraction, magnetization, AC susceptibility, and specific heat measurements. The defect-fluorite type of cubic structure, previously reported as the crystal structure of $\mathrm{E}{\mathrm{r}}_{2}\mathrm{Z}{\mathrm{r}}_{2}{\mathrm{O}}_{7}$, is consistent with our x-ray powder diffraction data. The measurements of physical properties were performed in magnetic field applied along principal crystallographic directions. A negligible directional dependence of physical properties is observed at temperatures down to 3 K, and only minor differences can be traced at lower temperatures. A low-temperature anomaly in magnetization and specific heat data and its evolution with applied magnetic field is followed. A frequency-dependent shift of freezing temperature was observed in AC susceptibility. Several origins of the observed anomaly are discussed, leaving a spin-glass state as the most probable explanation.