Structural investigations of (Mn, Dy) co-doped ZnO nanocrystals using X-ray absorption studies

Abstract

EXAFS measurements on sol gel derived (Mn, Dy) co-doped ZnO nanocrystals show that oxygen vacancies are created near the Dy sites into ZnO lattice. Thus, oxygen vacancy assisted bound magnetic polarons contribute to the RTFM in the Dy doped samples.

Diluted Magnetic Semiconductor ZnO: Magnetic Ordering with Transition Metal and Rare Earth Ions

“…Among these dopants, V, Cr, Mn, Co, Ni, and Cu are recognized as suitable dopants of ZnO for spintronic and magneto-optical communication devices due to their RTFM. In TM ions, the magnetization arises from partially filled 3d shells, and most of the cases since total orbital magnetic moment is zero, the magnetic moment is only due to the spin component, and hence total magnetic moment per atom is less [24]. Among TM/ZnO, Co deserved a special attention due to its highest magnetic moments (4.8 μ B ) and a positive magnetic exchange coupling constant [25].…”

“…In rare earth (RE) elements, magnetization appears due to unfilled 4f orbitals leading to higher magnetic moment per atom, though 4f electrons interacted with 5d or 6 s electrons [24], but exhibits weak exchange interaction with other RE ions, which is contrast to TM ions 3d electrons are directly interacted. The RE ion-doped ZnO has ferromagnetism that is induced by p-f hybridization via defect carriers [27].…”

“…The temperature-dependent magnetization (Figure 6b) via ZFC and FC at H = 100 Oe shows a typical FM behavior while no intersection is observed in the temperature region of 10-400 K, which reaffirms that T c is higher than 400 K. However, these FC/ZFC curves show the blocking temperature at T b = 90 K. The existence of the blocking temperature may result from intrinsic defects, such as oxygen vacancies [47], which contribute weak intrinsic ferromagnetism. The bifurcation begins to increase as the temperature goes below 100 K, and the effect of the external magnetic field starts to overcome the thermal fluctuation and dominate the overall magnetization when the temperature is lower than 100 K. Figure 6d shows the magnetic results at room temperature with simultaneous doping of Mn and Dy in ZnO nanoparticles prepared by sol-gel process (Mn = 0 and 2% and Dy = 0, 2, 4, and 6%) [24]. The M-H results show that as doping concentration of Dy is increased, magnetic behavior changes from weak ferromagnetic/ superparamagnetic to ferromagnetic states.…”

“…SQUID measurements: Magnetic moment (b) with temperature (c) with applied field, for ZnO/Mn nanowires. (d) M-H plots for ZnO/(Mn, Dy) nanoparticles (adapted from[24,44,46]).…”

Micro-structural, Morphological and Optical Properties of Pure and Metal (Mn & Mg) Doped ZnO Thin Films by Low Cost SILAR Method

“…The Mn/Mg doped ZnO thin films were prepared by different methods such as spray pyrolysis method, sol-gel, pulsed laser deposition, chemical bath deposition and SILAR method [18][19][20][21][22]. Among these methods, SILAR attracts more interests because it offers several advantages such as high chemical homogeneity, low processing temperature, possibility of controlling the size and morphology of particles, simplicity and low cost.…”