On the deviation from a Curie–Weiss behavior of the ZnFe2O4 susceptibility: A combined ab-initio and Monte-Carlo approach

Abstract

We present a numerical study of the magnetic properties of ZnFe2O4 using Monte-Carlo simulations performed considering a Heisenberg model with antiferromagnetic couplings determined by Density Functional Theory. Our calculations predict that the magnetic susceptibility has a cusp-like peak centered at 13 K, and follows a Curie–Weiss behavior above this temperature with a high and negative Curie–Weiss temperature (normalΘCW=−170 K). These results agree with the experimental data once extrinsic contributions that give rise to the deviation from a Curie–Weiss law are discounted. Additionally, we discuss the spin configuration of ZnFe2O4 below its ordering temperature, where the system presents a high degeneracy.

Effect of preparation methods on magnetic properties of stoichiometric zinc ferrite

“…However, a problem found in nanostructured high-energy milled spinel ferrites is related to its thermal stability owing to their small particle size, non-equilibrium cation distribution, [31] disordered spin configuration, [45,46] and high-chemical activity. [47] Because of their unstable character, decomposition of zinc ferrite into ZnO and/or hematite may occur as a result of a further thermal treatment. This work is aimed to understand the relation between microstructure and magnetic properties of ferrites by comparing XRD and magnetic properties measurements performed on samples prepared by the three most common synthesis methods (conventional ceramic, mechanochemical, and sol-gel synthesis) and powders of zinc ferrite supplied by Alpha Aesar.…”

Control of magnetic properties in spinel ZnFe2O4 thin films through intrinsic defect manipulation

“…The described magnetization behavior of films annealed at temperatures ≥330 • C is characteristic of a near-to-bulk normal spinel structure with antiferromagnetic spin alignment, therefore a lack of magnetic moment is expected at temperatures below the Néel temperature (≤12 K). 2,28,37 The bulk cationic distribution is probed by spectroscopic ellipsometry and investigated based on the strength of electronic transitions visible in the complex DF, ε = ε 1 + iε 2 . 19,22 The fit of the parametric model dielectric function (MDF) to the numerical approximation (B-Spline) for LP ZFO as well as individual function contributions to the MDF (ε 2 ) are depicted in Fig.…”

Multiplicity of Zn coordination sites at cubic spinel ferrites: magnetism and influence of the Zn d band.

“…As we will show later, setting U(Nid, Fed) = 4 eV is the best choice to properly describe the structural, electronic and magnetic properties of NFO under our theoretical conditions, and also to reproduce the ZFO experimental band gap around 2 eV [47,48]. Regarding U(Znd), previous DFT simulations of ZFO [8,9,40,[49][50][51] have considered different values, from 0 to 5 eV, but without performing a detailed study of its in uence on the obtained properties. We will address such study in the next sections.…”