Structural, magnetic and optical studies of Zn0.95Mn0.05O DMS (original) (raw)
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Comparative studies on Zn 0.95 Ni 0.05 O DMS synthesized by co-precipitation and ceramic methods
ZnO substituted with transitional metal ions at the cationic site present interesting magnetic properties due to the strong sp-d exchange interaction which are expected to play a vital role in SPINTRONICS applications. The preparation route plays a vital role in the synthesis of single phase oxide diluted magnetic semiconductors (DMS). Zn 0.95 Ni 0.05 O prepared by both co-precipitation and ceramic methods were analyzed in detail by powder X-ray diffraction. Pelleted samples examined for their magnetic property using vibrating sample magnetometer indicated ferromagnetic-like behavior at 300 K. Comparing the results of measurements performed on both the samples, we conclude co-precipitation method to be more effective in obtaining single phase compound with desirable properties by the relatively low temperature processing of the precipitated hydroxides.
Structural, magnetic and optical studies of (Zn 0.90Co 0.05Ni 0.05O) DMS
Materials Letters, 2010
ZnO DMS were prepared by co-precipitation method. Single phase Zn0.90Co0.05Ni0.05O was confirmed by powder X-ray diffraction (XRD). The samples were characterized by EDS to confirm the expected stoichiometry. SEM revealed no surface precipitation of dopants. Photoluminescence for pure ZnO was observed in the bluish green region. Compared to undoped ZnO, the luminescence of Co–Ni co-doped ZnO was strongly quenched. The samples were examined for its magnetic property using vibrating sample magnetometer (VSM) which indicated ferromagnetic behavior at room temperature with a coercivity of 123.37 g. XRD measurements showed impurity phase for samples prepared by ceramic method.
Journal of The European Ceramic Society, 2006
The reactivity of the Zn–Mn–O system, prepared by conventional ceramic routes using ZnO and MnO2 as starting materials are described and correlated with the magnetic response. X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy techniques have been used for the structural analysis. The ferromagnetic response is unambiguously determined to be due to the simultaneous presence of Mn+3 and Mn+4 ions at the Zn diffusion front into the manganese oxide grain. Thus, it is demonstrated that Mn does not incorporate into the ZnO lattice substitutionally, but it is the Zn that diffuses into the manganese oxide grains, acting as a retardant of the manganese reduction, Mn+4 → Mn+3. At the diffusion front, both ions coexist and their spins couple ferromagnetically through a double exchange mechanism. This mechanism explains the origin of the room temperature ferromagnetism recently discovered in Zn–Mn–O system as a promising material for spintronic devices.
A Perspective on Zinc Oxide Based Diluted Magnetic Semiconductors
Journal of Nano- and Electronic Physics, 2018
Diluted magnetic semiconductor (DMS) is envisaged to portray a substantial position in inter-punitive material science and prospect spintronics. The reason being spin and charge degrees of freedom are accommodated into solitary matter and their interaction is anticipated to probe innovative electronic devices. DMSs evince multifarious advantages such as wide band gap apposite for applications with short wavelength light, transparency and dye ability with pigments, high carrier concentration, capability to be cultivated even on plastic substrate at low temperature, green safety, durability , most importantly economical. Various theoretical and experimental research findings have been proposed on the ferromagnetic, paramagnetic, antiferromagnetic and spin glass properties at room-temperature of transition metal-doped DMSs such as TiO2, ZnO, Cu2O, SnO2, In2O3 etc in last few years. The objective of the paper is to comprehend the recent research advancement of ZnO based DMS specimens doped with various 3d transition metals.
Structural and Magnetic Properties of Codoped Zn O based Diluted Magnetic Semiconductors
diluted magnetic semiconductors are prepared by the sol-gel method. The structural and magnetic properties of the samples are studied using x-ray diffraction (XRD), extended x-ray absorption fine structure (EXAFS) and superconducting quantum interference device (SQUID). The XRD patterns does not show any signal of precipitates that are different from wurtzite type ZnO when Co content is lower than x = 0.10. An EXAFS technique for the Co K-edge has been employed to probe the local structures around Co atoms doped in ZnO powders by fluorescence mode. The simulation results for the first shell EXAFS signals indicate that Zn sites can be substituted by Co atoms when Co content is lower than x = 0.05. The SQUID results show that the samples (x < 0.05) exhibit clear hysteresis loops at 300 K, and magnetization versus temperature from 5 K to 350 K at H = 100 Oe for the sample x = 0.02 shows that the samples have ferromagnetism above room temperature. A double-exchange mechanism is proposed to explain the ferromagnetic properties of the samples.
Synthesis and characterization of single phase Mn doped ZnO
2009
Different samples of Zn1-xMnxO series have been prepared by conventional solid state sintering method. It has been identified, up to what extent of doping enable us to synthesize single-phase polycrystalline Mn doped ZnO samples which is one of the prerequisite for dilute magnetic semiconductor and we have analyzed its certain other physical aspects. In synthesizing the samples proportion of Mn varies from 1 at% to 5 at%. However the milling times have been varied (6, 12, 24, 48 & 96 hours) for only 2 at% Mn doped samples while for other samples (1, 3, 4 & 5 at% Mn doped) the milling time has been kept fixed at 96 hours. Room temperature X-Ray diffraction (XRD) data reveal that all of the prepared samples up to 3 at% of Mn doping exhibit wurtzite-type structure, no segregation of Mn and/or its oxides has been found. The 4 at% Mn doped samples show a weak peak of ZnMn2O4 apart from usual other peaks of ZnO and the intensity of this impurity peak has been further increased for 5 at% o...
Structural and magnetic properties of transition metal substituted ZnO
Journal of Applied Physics, 2004
Structural and magnetic properties have been studied for polycrystalline Zn1−xTMxO, where TM (transition metal ions) = Mn, Fe, and Co. No bulk ferromagnetism was observed for single-phase materials, contrary to the existing theories. Single-phase samples demonstrate paramagnetic Curie-Weiss behavior with antiferromagnetic interactions, similar to other diluted magnetic semiconductors. Non-optimal synthesis conditions lead to formation of second phases that are responsible for spin-glass behavior (ZnMnO3 impurity for Zn1−xMnxO (S. Kolesnik et al., J. Supercond.: Incorp. Novel Magn. 15, 251 (2002))) or high-temperature ferromagnetic ordering (Co metal for Zn1−xCoxO with the Curie temperature TC > 800 K or (Zn,Fe)3O4 for Zn1−xFexO with TC = 440 K).
Structural and Magnetic Properties of Transition-Metal-Doped Zn 1−x Fe x O
The ability to produce high-quality single-phase diluted magnetic semiconductors (DMS) is the driving factor to study DMS for spintronics applications. Fe-doped ZnO was synthesized by using a low-temperature co-precipitation technique producing Zn 1−x Fe x O nanoparticles (x = 0, 0.02, 0.04, 0.06, 0.08, and 0.1). Structural, Raman, density functional calculations, and magnetic studies have been carried out in studying the electronic structure and magnetic properties of Fe-doped ZnO. The results show that Fe atoms are substituted by Zn ions successfully. Due to the small ionic radius of Fe ions compared to that of a Zn ions, the crystal size decreases with an increasing dopant concentration. First-principle calculations indicate that the charge state of iron is Fe 2+ and Fe 3+ with a zinc vacancy or an interstitial oxygen anion, respectively. The calculations predict that the exchange interaction between transition metal ions can switch from the antiferromagnetic coupling into its quasi-degenerate ferromagnetic coupling by external perturbations. This is further supported and explains the observed ferromagnetic bahaviour at magnetic measurements. Magnetic measurements reveal that decreasing particle size increases the ferromagnetism volume fraction. Furthermore, introducing Fe into ZnO induces a strong magnetic moment without any distortion in the geometrical symmetry; it also reveals the ferromagnetic coupling.
Effect of Isovalent Doping on the Magnetic Properties of ZnMnO Diluted Magnetic Semiconductors
Journal of the Korean Physical Society, 2019
The magnetic properties of a ZnMnO diluted magnetic semiconductor isovalently doped with Mg and S have been successfully studied. ZnMnO alloys were prepared with different concentrations of magnesium and sulfur by using ultrasonic spray pyrolysis technique; additionally, the films were doped for free charge carriers by using nitrogen. For ZnMnO doped with 5% of Mg, the Curie temperature reached 104 K, and second-phase magnetic precipitates were observed with increasing Mg concentration. On the other hand, the sulfur doped ZnMnO showed an increased Curie temperature higher than room temperature due to increased number of holes which mediated the magnetic exchange interaction between magnetic ions.
Magneto-optical properties of the diluted magnetic semiconductor -type ZnMnO
2006
We present a magneto-optical study of p-type Zn 1−x Mn x O diluted magnetic semiconductors (DMS) obtained by thermal oxidation Zn 1−x Mn x Te layers. Photoluminescence spectra were used to determine the "giant" Zeeman splitting and to estimate the exchange integrals N 0 (α − β) ∼ 0.1 eV. This is an extremely small value for a II-VI DMS, and we discuss possible reasons for this effect.