Field-induced antiferromagnetic transition in CeIrIn$_5$

TL;DR

This study uses $^{115}$In NMR to investigate CeIrIn$_5$ under high magnetic fields, revealing a field-induced transition to an antiferromagnetic state with moments aligned along the field.

Contribution

First NMR evidence of a field-induced antiferromagnetic transition in CeIrIn$_5$ with moments aligned along the magnetic field direction.

Findings

NMR line intensity decreases due to shorter $T_2$ relaxation times.

$1/T_1$ peaks at the transition, indicating magnetic ordering.

Transition likely involves antiferromagnetic order with propagation vector $(1/2, 1/2, 0)$.

Abstract

We report low-temperature $^{115}$In nuclear magnetic resonance (NMR) study of the prototypical heavy-fermion compound CeIrIn$_5$ in high magnetic fields applied close to the crystallographic $c$ axis. For this orientation, a field-induced transition was previously reported to take place at about 28 T. Although we do not observe any change of the NMR spectrum above the transition, the intensity of the NMR lines drastically decreases as a consequence of a considerable shortening of the $T_2$ relaxation time. In addition, $1/T_1$ shows a pronounced maximum at the transition. Taking into account previous high-field de Haas-van Alphen results in conjunction with band-structure calculations, our NMR results are most naturally explained by the field-induced transition into an antiferromagnetic state with the propagation vector $\mathbf{Q} = (1/2, 1/2, 0)$ and magnetic moments aligned antiferromagnetically along the $c$ axis. This makes CeIrIn$_5$ a unique case where the application of the magnetic field induces an ordered state with moments antiferromagnetically aligned along the field direction.