Novel Itinerant Antiferromagnet TiAu

TL;DR

This paper reports the discovery of TiAu, the first known itinerant antiferromagnet without magnetic constituents, providing new insights into weak itinerant antiferromagnetism and the role of spin fluctuations.

Contribution

It introduces TiAu as the first itinerant antiferromagnet with no magnetic elements, challenging existing theories and advancing understanding of spin fluctuations in such systems.

Findings

Antiferromagnetic order below T_N ~ 36 K in TiAu

TiAu is the first itinerant antiferromagnet without magnetic constituents

Spin fluctuations are significant at low temperatures in TiAu

Abstract

Itinerant and local moment magnetism have substantively different origins, and require distinct theoretical treatment. A unified theory of magnetism has long been sought after, and remains elusive, mainly due to the limited number of known itinerant magnetic systems. In the case of the two such examples discovered several decades ago, the itinerant ferromagnets ZrZn_2 and Sc_3In, the understanding of their magnetic ground states draws on the existence of 3d electrons subject to strong spin fluctuations. Similarly, in Cr, an elemental itinerant antiferromagnet (IAFM) with a spin density wave (SDW) ground state, its 3d character has been deemed crucial to it being magnetic. Here we report the discovery of the first IAFM compound with no magnetic constituents, TiAu. Antiferromagnetic order occurs below a Neel temperature T_N ~ 36 K, about an order of magnitude smaller than in Cr, rendering the spin fluctuations in TiAu more important at low temperatures. This new IAFM challenges the currently limited understanding of weak itinerant antiferromagnetism, while providing long sought-after insights into the effects of spin fluctuations in itinerant electron systems.