Induced antiferromagnetism and large magnetoresistances in RuSr2(Nd,Y,Ce)2Cu2O10-d ruthenocuprates

TL;DR

This study investigates RuSr2(Nd,Y,Ce)2Cu2O10-d ruthenocuprates, revealing distinct Ru and Cu magnetic orders, induced antiferromagnetism, and large magnetoresistances linked to electronic phase transitions and potential superconducting fluctuations.

Contribution

It reports the first detailed phase diagram showing separate Ru and Cu magnetic transitions and the induced Cu antiferromagnetic phase in ruthenocuprates.

Findings

Distinct Ru and Cu spin ordering transitions identified.

Large negative magnetoresistances observed in specific doping regions.

Collapse of MR and magnetisation suggests onset of superconducting fluctuations.

Abstract

RuSr2(Nd,Y,Ce)2Cu2O10-d ruthenocuprates have been studied by neutron diffraction, magnetotransport and magnetisation measurements and the electronic phase diagram is reported. Separate Ru and Cu spin ordering transitions are observed, with spontaneous Cu antiferromagnetic order for low hole doping levels p, and a distinct, induced-antiferromagnetic Cu spin phase in the 0.02 < p < 0.06 pseudogap region. This ordering gives rise to large negative magnetoresistances which vary systematically with p in the RuSr2Nd1.8-xY0.2CexCu2O10-d series. A collapse of the magnetoresistance (MR) and magnetisation in the pre-superconducting region may signify the onset of superconducting fluctuations.