We report that the local Ising anisotropy in pyrochlore oxides - the crucial requirement for realizing the spin-ice state - can be broken by means of high magnetic fields. For the case of the well-established classical spin-ice compound Ho2Ti2O7 the magnetization exceeds the angle-dependent saturation value of the Ising limit using ultra-high fields up to 120 T. However, even under such extreme magnetic fields full saturation cannot be achieved. Crystal-electric-field calculations reveal that a level crossing for two of the four ion positions leads to magnetization steps at 55 and 100 T. In addition, we show that by using a field sweep rate in the range of the spin-relaxation time the dynamics of the spin system can be probed. Exclusively at 25 ns/T a new peak of the susceptibility appears around 2 T. We argue, this signals the cross-over between spin-ice and polarized correlations.
@article{arxiv.1902.02990,
title = {Magnetization beyond the Ising limit of Ho$_2$Ti$_2$O$_7$},
author = {L. Opherden and T. Herrmannsdörfer and M. Uhlarz and D. I. Gorbunov and A. Miyata and O. Portugall and I. Ishii and T. Suzuki and H. Kaneko and H. Suzuki and J. Wosnitza},
journal= {arXiv preprint arXiv:1902.02990},
year = {2019}
}
Comments
7 pages, 4 figures, accepted for publication in Phys. Rev. B