Carrier-mediated ferromagnetism and dielectric tailoring in dual-doped ZnO semiconductor nanoparticles for spintronics
Rajwali Khan, Asif Rasool, Shahnaz Kossar, Ejaz Ahmad Khera, Khaled Althubeiti, Sattam Al Otaibi, Sherzod Abdullaev, Nasir Rahman, Akif Safeen, Shahid Iqbal
Abstract
The research and development of modified nanomaterials is critical for spin-based electronics storage systems, particularly novel magnetic materials with 100 % spin polarization at room temperature. This feature is present in a number of Zintl group compounds and should be investigated. This work thoroughly investigated the impact of (Co, Eu) co-doping on the structural, electrical, dielectric, and ferromagnetic properties of ZnO nanoparticles. At all doping concentrations, the tetragonal phase was retained, according to X-ray diffraction (XRD) examination. Dielectric investigations showed that while the dielectric constant (ε r' ) and dielectric loss ( ε '') decreased with increasing Eu content, the frequency-dependent improvement of AC electrical conductivity (σ AC ) was ascribed to charge hopping among nanograins and dielectric relaxation impacts. Magnetic studies were presented to explore the ferromagnetic response further, revealing a shift from diamagnetic behavior in pure ZnO to robust room-temperature ferromagnetism (RTFM) in Co-doped and (Co, Eu) co-doped ZnO nanoparticles. Strong carrier-mediated exchange contacts and defect-induced magnetism were shown by the increased remanent magnetization (Mr) and coercivity (Hc) that accompanied increasing Eu content, peaking at 5 % Eu doping. Ferromagnetic ordering with a Curie temperature (T C ) of roughly 370 K for optimally doped materials was validated by Arrott plot analysis. The exchange interactions, defect-induced effects, and structural deformation all contribute to the magnetism in ZnO caused by Co and Eu doping. While Eu 3+ participates by forming partially filled 4f orbitals, Cobalt (Co 2+ ) ions contribute localized magnetic moments because of unpaired 3d electrons when they substitute Zn 2+ in the ZnO lattice. These dopants interaction facilitates long-range ferromagnetic coupling via carrier-mediated exchange processes, which include bound magnetic polarons (BMPs), in which oxygen vacancies trap charge carriers. The findings show that co-doped ZnO ferromagnetic behavior may be efficiently modulated by controlled Eu co-doping, which makes these materials attractive options for spintronic applications.