Giant Anisotropy of Magnetoresistance and "Spin Valve" effect in Antiferromagnetic $Nd_{2-x}Ce_xCuO_{4}$

TL;DR

This study reveals a giant anisotropy in magnetoresistance and a spin valve effect in antiferromagnetic Nd2-xCexCuO4, driven by field-induced spin-flop transitions, highlighting complex charge-spin entanglement.

Contribution

It introduces the observation of giant anisotropic magnetoresistance and a spin valve effect in Nd2-xCexCuO4, linked to spin-flop transitions, advancing understanding of charge-spin interactions in antiferromagnets.

Findings

Giant anisotropy in MR below 5 K.

Resistivity can be tuned by magnetic field direction.

Field-induced spin-flop transition explains anisotropy.

Abstract

We have studied anisotropic magnetoresistance (MR) and magnetization with rotating magnetic field (B) within $CuO_2$ plane in lightly doped AF $Nd_{2-x}Ce_xCuO_{4}$. \emph{A giant anisotropy} in MR is observed at low temperature below 5 K. The c-axis resistivity can be tuned about one order of magnitude just by changing B direction within $CuO_2$ plane and a scaling behavior between out-of-plane and in-plane MR is found. A "Spin valve" effect is proposed to understand the giant anisotropy of out-of-plane MR and the evolution of scaling parameters with the external field. It is found that the field-induced spin-flop transition of Nd$^{3+}$ layer under high magnetic field is the key to understand the giant anisotropy. These results suggest that a novel entanglement between charge and spin dominates the underlying physics.