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arXiv · 1902.02990

Magnetization beyond the Ising limit of Ho$_2$Ti$_2$O$_7$

L. Opherden·T. Herrmannsdörfer·M. Uhlarz·D. I. Gorbunov·A. Miyata·O. Portugall·I. Ishii·T. Suzuki·H. Kaneko·H. Suzuki·J. Wosnitza
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Abstract

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 Ho$_2$Ti$_2$O$_7$ 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.

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L. Opherden, T. Herrmannsdörfer, M. Uhlarz, D. I. Gorbunov, A. Miyata, O. Portugall, I. Ishii, T. Suzuki, H. Kaneko, H. Suzuki, J. Wosnitza. 2019-02-08. Magnetization beyond the Ising limit of Ho$_2$Ti$_2$O$_7$. https://doi.org/10.1103/physrevb.99.085132

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