Field-Induced Ordering in Dipolar Spin Ice

TL;DR

This study uses numerical simulations to explore how a magnetic field tilted from the [111] axis induces a first-order transition in dipolar spin ice, revealing the role of dipolar interactions in ordering phenomena.

Contribution

It demonstrates the field-induced transition from kagome ice to a q=X state and clarifies the microscopic origin of this ordering, aligning with experimental observations.

Findings

First-order transition from kagome ice to q=X state under tilted field

Antiferromagnetic alignment of spin chains causes ordering

Residual entropy of kagome ice is fully recovered

Abstract

We present numerical studies of dipolar spin ice in the presence of a magnetic field slightly tilted away from the [111] axis. We find a first-order transition from a kagome ice to a $\mathbf{q}=$X state when the external field is tilted toward the $[11\bar{2}]$ direction. This is consistent with the anomalous critical scattering previously observed in the neutron scattering experiment on the spin ice material $\textrm{Ho}_{2}\textrm{Ti}_{2}\textrm{O}_{7}$ in a tilted field [Nat. Phys. 3, 566 (2007)]. We show that this ordering originates from the antiferromagnetic alignment of spin chains on the kagome planes. The residual entropy of the kagome ice is fully recovered. Our result captures the features observed in the experiments and points to the importance of the dipolar interaction in determining ordered states in the spin ice materials. We place our results in the context of recent susceptibility measurements on $\textrm{Dy}_{2}\textrm{Ti}_{2}\textrm{O}_{7}$, showing two features for a [111] field.