Reproducibility of room temperature ferromagnetism in Zn0.95Mn0.05O and its understanding

TL;DR

This study successfully reproduces and investigates the room temperature ferromagnetism in Mn-doped ZnO, demonstrating how mechanical milling-induced disorder and grain size reduction enhance magnetic properties up to 640 K.

Contribution

It provides a detailed understanding of how mechanical milling influences ferromagnetism in Mn-doped ZnO, emphasizing the role of lattice diffusion and disorder.

Findings

Ferromagnetism extended up to 640 K in milled samples.

Grain size reduction correlates with increased magnetic moment.

Mechanical milling induces disorder that enhances ferromagnetic ordering.

Abstract

The present work reproduces the room temperature ferromagnetism by doping magnetic Mn atoms in diamagnetic ZnO. The ferromagnetic ordering is extended up to 640 K in mechanical milled Zn0.95Mn0.05O samples. The bulk and nanocrystalline samples are stabilized in hexagonal crystal structure with space group p63mc. The grain size and lattice strain of the samples, estimated from XRD spectrum using Williamson-Hall plot, showed a significant variation with milling time. Surface structure (morphology, distribution of grains and elements) is observed to be reasonably good from SEM picture and EDX spectrum at room temperature. The ferromagnetic ordering in bulk, milled and alloyed samples is primarily due to the diffusion of Mn(2+) ions into the lattice sites of ZnO. The enhancement of magnetic moment and ferromagnetic ordering temperature with reducing the grain size is discussed in terms of the existing theoretical predictions and experimental works. The role of mechanical milling induced disorder for the enhancement of room temperature ferromagnetism in Zn0.95Mn0.05O (dilute magnetic semiconductor) is also highlighted.