Spin freezing in the pyrochlore antiferromagnet Pr₂Zr₂O₇

We report on the low temperature magnetism of pyrochlore oxide Pr₂Zr₂O₇. The crystal electric field ground state in Pr³⁺ (4f², J = 4) ions has non-Kramers doublet with local <111> Ising magnetic anisotropy. The negative Curie-Weiss temperature below 10 K (-0.55 K) indicates an antiferromagnetic coupling between the spins. The AC magnetic susceptibility does not exhibit any long range ordering at least down to 76 mK. Instead, a frequency dependence of AC magnetic susceptibility is observed below 0.3 K, indicating a spin freezing behavior. Furthermore, recently we have succeeded for the first time in growing a single crystal of Pr₂Zr₂O₇ by the floating-zone method using an infrared furnace equipped with four Xe lamps. We will also comment on the crystal growth of Pr₂Zr₂O₇.