Carrier driven antiferromagnetism and exchange-bias in SrRuO3/CaRuO3 heterostructures

TL;DR

This study reveals that in SrRuO3/CaRuO3 heterostructures, the conduction electrons induce antiferromagnetic order and exchange bias in CaRuO3, highlighting a novel magnetic ordering mechanism driven by interface effects.

Contribution

The paper uncovers a new magnetic ordering mechanism in oxide heterostructures, showing how SrRuO3 induces antiferromagnetic order and exchange bias in CaRuO3 through interface-driven electron polarization.

Findings

CaRuO3 develops dual magnetic character with net moment and antiferromagnetic order.

Exchange bias observed at low temperatures due to induced polarization.

Ab initio simulations support the proposed polarization mechanism.

Abstract

Oxide heterostructures exhibit a rich variety of magnetic and transport properties which arise due to contact at an interface. This can lead to surprising effects that are very different from the bulk properties of the materials involved. We report the magnetic properties of bilayers of SrRuO3, a well known ferromagnet, and CaRuO3, which is nominally a paramagnet. We find intriguing features that are consistent with CaRuO3 developing dual magnetic character, with both a net moment as well as antiferromagnetic order. We argue the ordered SrRuO3 layer induces an undulating polarization profile in the conduction electrons of CaRuO3, by a mechanism akin to Friedel oscillations. At low temperatures, this oscillating polarization is inherited by rigid local moments within CaRuO3, leading to a robust exchange bias. We present ab initio simulations in support of this picture. Our results demonstrate a new ordering mechanism and throw light on the magnetic character of CaRuO3 .