Absence of Ferromagnetism in Mn-doped Tetragonal Zirconia

TL;DR

This study experimentally investigates Mn-doped tetragonal zirconia and finds no evidence of ferromagnetism, contrary to prior theoretical predictions, showing paramagnetic and antiferromagnetic behaviors instead.

Contribution

It provides the first experimental validation showing the absence of ferromagnetism in Mn-doped tetragonal zirconia, challenging previous theoretical predictions.

Findings

Mn ions are in Mn3+ oxidation state with local magnetic moments.

Samples up to 10% Mn doping are paramagnetic with antiferromagnetic interactions.

Higher Mn doping shows local ferrimagnetic ordering, but no ferromagnetism observed.

Abstract

In a recent letter, it has been predicted within first principle studies that Mn-doped ZrO2 compounds could be good candidate for spintronics application because expected to exhibit ferromagnetism far beyond room temperature. Our purpose is to address this issue experimentally for Mn-doped tetragonal zirconia. We have prepared polycrystalline samples of Y0.15(Zr0.85-yMny)O2 (y=0, 0.05, 0.10, 0.15 & 0.20) by using standard solid state method at equilibrium. The obtained samples were carefully characterized by using x-ray diffraction, scanning electron microscopy, elemental color mapping, X-ray photoemission spectroscopy and magnetization measurements. From the detailed structural analyses, we have observed that the 5% Mn doped compound crystallized into two symmetries (dominating tetragonal & monoclinic), whereas higher Mn doped compounds are found to be in the tetragonal symmetry only. The spectral splitting of the Mn 3s core-level x-ray photoelectron spectra confirms that Mn ions are in the Mn3+ oxidation state and indicate a local magnetic moment of about 4.5 {\mu}B/Mn. Magnetic measurements showed that compounds up to 10% of Mn doping are paramagnetic with antiferromagnetic interactions. However, higher Mn doped compound exhibits local ferrimagnetic ordering. Thus, no ferromagnetism has been observed for all Mn-doped tetragonal ZrO2 samples.