Investigation of bulk magneto-resistance crossovers in iron doped zinc-oxide using spectroscopic techniques

Abstract

Pellets of Pure and Fe-doped dilute magnetic semiconducting (DMS) samples are studied for bulk magneto-resistance (BMR) at room temperature and at low-temperatures ∼100K. Raman-, photoluminescence- and X-ray photoelectron-spectroscopic techniques are used to determine chemical and electronic structures of the samples. A broadband intense yellow-green-orange luminescence is observed in Fe-doped ZnO samples and emission red-shifts are investigated. Electrical transport is studied with and without applied magnetic field up to 9T and thermal activation and hopping modes of conduction is discussed in light of nature of Fe substitution in the host lattice. Several decremental- to incremental-BMR crossovers are obtained corresponding to experimental variables of Fe concentration 0.025 ≤ x ≤ 0.1, temperature and applied magnetic field. Several possible modes of magneto-transport are discussed to further elucidate the origin of the as-found BMR crossovers in our samples. Positive BMR in pure- and highly doped (x ≥ 0.1) ZnO is found to originate from F-centers and thermal fluctuations, respectively. However, modestly doped (x ≤ 0.05) ZnO exhibit thermally activated conduction and magnetic poloron mediated negative BMR.

Entropy generation analysis for mixed convection flow of nanofluid due to vertical plate with chemical reaction effects

“…For the system described in Eqs. ( 5 ) to ( 8 ), the following giving entropy generation relations are created to maximize heat transmission and reduce energy losses 1 , 2 , 13 . …”

“…Khan et al 1 discussed the exclusive features of nanofluids which report enhancement in the power systems and elctrinc charge systems. Ali et al 2 reported iron zinc nanoparticles via spectroscopic approach. Qayyum et al 3 examined the blood fluid properties for suspension of MWCNTs via stretching disk.…”

Applications of Nano-biofuel cells for Reiner-Philippoff nanoparticles with higher order slip effects

“…Maatoug et al 13 claimed the hydraulic systems applications for nanofluid via lubricated surface. Ali et al 14 executed heat transfer observations for iron doped zinc-oxide nanoparticles following the bulk motion. The rotating flow due to stretchable disk with nanofluid interaction was examined by Qayyum et al 15 .…”

Enhanced Anticorrosion Properties and Mechanism of Co/N Codoped Modified ZnO Dilute Magnetic Solid Solutions

“…As an important smart material, ferromagnetic materials are widely used in various fields based on the strong correlation between their magnetic, electrical, and optical properties. Dilute magnetic semiconductors as a major branch of ferromagnetic materials, especially dilute magnetic solid solutions (DMSs) formed by magnetic transition metals Fe, Co, Ni, Cu, Mn, alkaline earth metal, or rare-earth doping, are intensively studied , and applied in storage, theoretical calculation, magnetic sensing, photoluminescence, photocatalysis, integrated circuits, spintronic devices, and electrochemical corrosion protection because of the simultaneous existence of both sp–d and d–d spin exchange. ZnO with a typical hexagonal fibrillated zincite structure has become a new third-generation multifunctional group II–VI semiconductor material with a wide range of applications due to its high chemical stability, heat resistance, wide confinement band, and large exciton binding energy. , Goktas et al studied the magnetic properties of Mn-doped ZnO at different pH and temperatures, which opened up a variety of possibilities for spintronic-based device applications.…”