Vibrating-Coil Magnetometry of the Spin Liquid Properties of Tb2Ti2O7

We have explored the spin liquid state in Tb2Ti2O7 with vibrating-coil magnetometry down to similar to 0.04 K under magnetic fields up to 5 T. We observe magnetic history dependence below T* similar to 0.2 K reminiscent of the classical spin ice systems Ho2Ti2O7 and Dy2Ti2O7. 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 Tb2Ti2O7 is akin to an incipient AIAO antiferromagnet.