Thermal relaxation of field-induced irreversible ferromagnetic phase in Pr-doped manganites

TL;DR

This study explores the magnetic and transport behaviors of Pr-doped manganites, revealing a stable, irreversible ferromagnetic state induced by magnetic fields, distinct from spontaneous or reversible transitions, linked to Mn spin reorientation.

Contribution

It uncovers a novel irreversible ferromagnetic phase in Pr-doped manganites caused by field-induced spin reorientation, differing from known reversible or spontaneous ferromagnetic states.

Findings

Field-induced FM state remains stable for over 10^5 seconds after field removal.

The FM transition is metamagnetic and irreversible, unlike typical reversible transitions.

The phenomenon is explained by Mn spin reorientation pinned by Pr moments.

Abstract

We have investigated the magnetic and transport properties of Pr$_{0.65}$Ca$_{0.35}$MnO$_3$ and Pr$_{0.82}$Na$_{0.18}$MnO$_3$ with almost same doping level under various magnetic fields. Upon applying a field of 4 T, both compounds undergo a metamagnetic transition from antiferromagnetic (AFM) to ferromagnetic (FM) in the low temperature region. The field-induced FM state is very stable for at least 10$^5$ s even after removing the field. This irreversible FM behavior is different from the spontaneous FM ordering as well as the FM state in a reversible metamagnetic transition. We discuss this unusual FM phenomenon found in the Pr-doped manganites with the AFM ground state in terms of the reorientation of Mn spins pinned by localized Pr moments.