Anisotropic Release of the Residual Zero-point Entropy in the Spin Ice Compound Dy2Ti2O7: Kagome-ice Behavior

TL;DR

This study investigates the anisotropic release of residual zero-point entropy in Dy2Ti2O7 spin ice, revealing how magnetic field direction influences frustration dimensionality and entropy behavior at very low temperatures.

Contribution

It demonstrates the anisotropic entropy release in Dy2Ti2O7 under magnetic fields, highlighting the transition from 3D pyrochlore to 2D Kagome-like lattice structures.

Findings

Residual entropy is nearly fully released at high fields along all directions.

Entropy behavior differs significantly in the intermediate field region for [111] direction.

Frustration structure transitions from 3D to 2D Kagome-like lattice under certain conditions.

Abstract

We report the specific heat and entropy of single crystals of the spin ice compound Dy2Ti2O7 at temperatures down to 0.35 K. We apply magnetic fields along the four characteristic directions: [100], [110], [111] and [112]. Because of Ising anisotropy, we observe anisotropic release of the residual zero-point entropy, attributable to the difference in frustration dimensionality. In the high magnetic field along these four directions, the residual entropy is almost fully released and the activation entropy reaches Rln2. However, in the intermediate field region, the entropy in fields along the [111] direction is different from those for the other three field directions. For the [111] direction the frustration structure changes from that of three-dimensional(3D) pyrochlore to that of two-dimensional(2D) Kagome-like lattice with constraint due to the ice rule, leading to different values of zero-point entropy.