High temperature onset of field-induced transitions in the spin-ice compound Dy2Ti2O7

TL;DR

This study investigates the temperature and magnetic field effects on spin ice behavior in Dy2Ti2O7, revealing the onset of local order and monopole-like excitations at relatively high temperatures.

Contribution

It demonstrates that monopole-based models can describe spin ice phenomena even at higher temperatures where monopoles are not well-defined quasiparticles.

Findings

Identification of a field feature at ~1.0 T indicating local spin ice order

Observation of frequency-dependent susceptibility related to kinetic constraints

Evidence supporting monopole picture applicability at elevated temperatures

Abstract

We have studied the field-dependent ac magnetic susceptibility of single crystals of Dy2Ti2O7 spin ice along the [111] direction in the temperature range 1.8 K - 7 K. Our data reflect the onset of local spin ice order in the appearance of different field regimes. In particular, we observe a prominent feature at approximately 1.0 T that is a precursor of the low-temperature metamagnetic transition out of field-induced kagome ice, below which the kinetic constraints imposed by the ice rules manifest themselves in a substantial frequency-dependence of the susceptibility. Despite the relatively high temperatures, our results are consistent with a monopole picture, and they demonstrate that such a picture can give physical insight to the spin ice systems even outside the low-temperature, low-density limit where monopole excitations are well-defined quasiparticles.