Vibrating-coil magnetometry of the spin liquid properties of Tb ₂Ti ₂O ₇

We have explored the spin liquid state in Tb ₂Ti ₂O ₇ with vibrating-coil magnetometry down to ∼0.04K under magnetic fields up to 5 T. We observe magnetic history dependence below T ^*∼0.2K reminiscent of the classical spin ice systems Ho ₂Ti ₂O ₇ and Dy ₂Ti ₂O ₇. The magnetic phase diagram inferred from the magnetization is essentially isotropic, without evidence of magnetization plateaus as anticipated for so-called quantum spin ice, predicted theoretically for [111] when quantum fluctuations renormalize the interactions. Instead, the magnetization for T T ^* agrees semiquantitatively with the predictions of "all-in-all-out" (AIAO) antiferromagnetism. Taken together, this suggests that the spin liquid state in Tb ₂Ti ₂O ₇ is akin to an incipient AIAO antiferromagnet.