Magnetic Ordering in the Spin-Ice Candidate Ho$_2$Ru$_2$O$_7$

TL;DR

This study uses neutron scattering to explore magnetic phase transitions in Ho$_2$Ru$_2$O$_7$, revealing sequential ordering of Ru and Ho sublattices and their interactions affecting spin-ice behavior.

Contribution

It provides the first detailed neutron scattering analysis of magnetic ordering and crystal field shifts in Ho$_2$Ru$_2$O$_7$, highlighting the interplay between Ru and Ho magnetic moments.

Findings

Two magnetic transitions at 95 K and 1.4 K to long-range order.

Ru moments disrupt the spin-ice state and induce Ho ordering.

Detected slight shifts in Ho$^{3+}$ crystal field levels at 95 K.

Abstract

Neutron scattering measurements on the spin-ice candidate material Ho$_2$Ru$_2$O$_7$ have revealed two magnetic transitions at T $\sim$ 95 K and T $\sim$ 1.4 K to long-range ordered states involving the Ru and Ho sublattices, respectively. Between these transitions, the Ho$^{3+}$ moments form short-ranged ordered spin clusters. The internal field provided by the ordered S=1 Ru$^{4+}$ moments disrupts the fragile spin-ice state and drives the Ho$^{3+}$ moments to order. We have directly measured a slight shift in the Ho$^{3+}$ crystal field levels at 95 K from the Ru ordering.