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

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.

7 pages, 4 figures, accepted for publication in Phys. Rev. B

References in corpus (5)

• Pinch Points and Kasteleyn Transitions: How Spin Ice Changes its Entropy
• Physical properties of a candidate quantum spin-ice system Pr2Hf2O7
• Observing Monopoles in a Magnetic Analog of Ice
• First order metamagnetic transition in Ho2Ti2O7 observed by vibrating coil magnetometry at milli-Kelvin temperatures
• Ultrasonic investigations of spin-ices Dy${}_2$Ti${}_2$O${}_7$ and Ho${}_2$Ti${}_2$O${}_7$ in and out of equilibrium