The origin of persistent spin dynamics and residual entropy in the stuffed spin iceHo2.3Ti1.7O7−δ

Abstract

Listen

Translate article

The so-called ‘spin ices’ form when exchange interactions, crystal fields, and dipolarinteractions are in a delicate balance. This gives rise to a ground state which has aconsiderable amount of residual spin entropy, much like the proton entropy in waterice through the freezing transition. Recently, ‘stuffed’ spin ices have provideda means to probe how delicate a balance is needed to stabilize the disorderedground state. Surprisingly, it is found that an increase of the density of spinsresults in very little change in the residual entropy, which leads to the interestingidea that residual entropy states might be more common than once believed formagnetism. In this communication, we detail the crystal growth of stuffed spin iceHo2.3Ti1.7O7−δ, and we complete neutron scattering experiments to observe how the spins order at lowtemperatures. It is found that even with this large perturbation, the system still has somekey signatures of the spin ice state, but the spin dynamics is significantly altered. With thisnew data, an explanation emerges for the zero-point entropy in the stuffed spin ices.