Anomalous ferromagnetic spin fluctuations in an antiferromagnetic insulator Pr_{1-x}Ca_{x}MnO_{3}

TL;DR

This study reveals that in an antiferromagnetic insulator, ferromagnetic spin fluctuations exist at high temperatures, decrease sharply at charge ordering, and vanish at the antiferromagnetic transition, highlighting the role of spin order.

Contribution

It uncovers the behavior of ferromagnetic spin fluctuations in an antiferromagnetic insulator and their dependence on charge and magnetic ordering temperatures.

Findings

Ferromagnetic fluctuations are present at high temperatures.

Fluctuations decrease sharply at charge ordering temperature.

Fluctuations vanish at the antiferromagnetic transition.

Abstract

The high temperature paramagnetic state in an antiferromagnetic (AFM) insulator Pr_{1-x}Ca_{x}MnO_{3} is characterized by the ferromagnetic (FM) spin fluctuations with an anomalously small energy scale. The FM fluctuations show a precipitous decrease of the intensity at the charge ordering temperature T_{CO}, but persist below T_{CO}, and vanish at the AFM transition temperature T_{N}. These results demonstrate the importance of the spin ordering for the complete switching of the FM fluctuation in doped manganites.