Structural and magnetic studies on Zr doped ZnO diluted magnetic semiconductor

G. Murtaza,R. Ahmad,M.S. Rashid,M. Hassan,A. Hussnain,Muhammad Azhar Khan,M. Ehsan ul Haq,M.A. Shafique,S. Riaz 한국물리학회 2014 Current Applied Physics Vol.14 No.2

In this study, Zirconium doped Zn1xZrxO (with x ¼ 0.00e0.10) samples have been prepared by formal solid-state reaction technique. The Zr doped ZnO samples annealed at 1100 C and characterized by different characterization techniques, such as X-ray diffraction (XRD), Scanning electron microscope (SEM), Vibrating sample magnetometer (VSM) and Fourier transform infrared spectroscopy (FTIR). The Xray diffraction (XRD) used to study the structural properties. XRD pattern showed that lattice parameters, “a”, “c”, unit cell volume and ZneO bond length increase with doping content (x 0.04) where as these decrease with x > 0.04. On the other hand, reverse trend observed with lattice distortion. The crystallite size decreases with increasing doping content of Zr. FTIR employed to investigate functional chemical bonding properties of different elements and compounds present in materials. The low, medium and high frequency absorption bands observed at 630, 1500 and 3435 cm1, which were the common features of ZneO, HeOeH and OeH bond respectively. SEM used to study surface morphology and measured grain size of specimen. The surface becomes dense and grain size decreases with increasing degree of Zr contents. The SEM micrograph also shows the presence of spherical micro size particles and formation of pores in samples. Magnetic properties were obtained using VSM. The samples exhibit room temperature ferromagnetism. The magnetic hysteresis loops show variation in the value of magnetic parameter. The saturation magnetization (Ms) and coercivity (Hc) decrease, while remanence magnetization (Mr) shows gradually increasing trend with Zr content. VSM measurement reveals that sample Zn0.96Zr0.4O show better result as compared to x ¼ 0.06e0.10.

First principle study of vanadium doped ZnS: Structural, electronic, elastic, magnetic and optical properties using mBJ approximation

Q. Mahmood,G. Murtaza,R. Ahmad,T. Hussain,I.G. Will 한국물리학회 2016 Current Applied Physics Vol.16 No.3

The structural, electronic, magnetic, mechanical and optical properties of ternary Zn1xVxS (x ¼ 0.0, 0.25, 0.50, 0.75 and 1.0) ferromagnetic semiconductor alloys have been studied in the zinc blende (ZB) phase, by first principle approach. Density functional theory has been employed to calculate the fundamental properties of the alloys using full-potential linearized augmented plane-wave plus the local orbitals (FPLAPW þ Lo) method. In addition, the electronic and magnetic properties are investigated by the local spin density approximation coupled with the modified BeckeeJohnson exchange potential (mBJLDA). Structural analysis revealed that the structure of the three alloys Zn0.75V0.25S, Zn0.50V0.50S, and Zn0.25V0.75S are stable in the ferromagnetic phase. It is noted that the calculated lattice constant decreases, while the bulk modulus increases with the increase of V content. The density of states and spin polarized band structure investigation demonstrated the half-metallic ferromagnetic characteristics of the investigated alloys and are also used to determines ped exchange constants N0a and N0b, due to S (p) eV(3d) hybridization. These results reveal that magnetic moment of V dopant element reduced from its free space value of 3 mB, because the Zn and S sites acquire minor atomic magnetic moments. The energy band gap analysis show an increasing trend with V doping that makes our compound a suitable candidate for the fabrication of devices operating in the ultraviolet region. Moreover, the static dielectric constant, ε1 (u), and static refractive index, n (u), increases with V contents. The incorporation of V generates some new peaks in the energy regions of 0e2.83 eV and 4e10 eV. The substitution by V increases the intensity of the peaks, and a slight red shift has been observed in the absorption peak. The extinction coefficient k (u) and optical conductivity also follow a similar trend to that of the dielectric constants. These results give deep insight into the design of devices for optical and spintronics applications using V doped ZnS.

First principles investigations of electronics, magnetic, and thermoelectric properties of rare earth based PrYO3(Y¼Cr, V) perovskites

B. Sabir,G. Murtaza,Q. Mahmood,R. Ahmad,K.C. Bhamu 한국물리학회 2017 Current Applied Physics Vol.17 No.11

The structural, electronic, magnetic, optical and thermoelectric properties of PrYO3(Y¼Cr, V) have been studied by using density functional based FP-LAPWþ lo method as implemented into WIEN2k code. The analysis of band structures and density of states confirm the half metallic ferromagnetism in studied compounds. The nature and origin of ferromagnetism has been depicted in terms of crystal field energies, exchange energies involved and exchange constants. Moreover, the reduction of magnetic moment from V/Cr, Pr sites and generation of small magnetic moments on oxygen and interstitials sites leads to negative value of indirect exchange energy Dx(pd) and strong hybridization. Finally, the thermoelectric behavior has been explained by discussing the electrical conductivity, thermal conductivity, Seebeck coefficient, power factor and thermal efficiency. Moreover, evaluation of PrYO3 on the basis of its magnetic and thermoelectric properties conform that the compounds are much suitable for spintronic and thermoelectric applications.

Ab-initio study of Li based chalcopyrite compounds LiGaX2 (X= S, Se, Te) in tetragonal symmetry: A class of future materials for optoelectronic applications

M.S. Yaseen,G. Murtaza,Rana M. Arif Khalil 한국물리학회 2018 Current Applied Physics Vol.18 No.10

Structural, electronic, optical, and thermoelectric aspects of chalcopyrite LiGaX2 (X=S, Se and Te) compounds have been investigated by density functional theory (DFT) based Wien2k simulator. The optimized ground state parameters are calculated by Wu-Cohen generalized gradient approximation (WC-GGA) and electronic structures, which have been further improved by modified Becke-Johnson (mBJ) potential. Moreover, a comparative study is given among the contribution of three anions (S, Se and Te) in the same symmetry of tetragonal phase. The calculated band gaps of the studied compounds are 3.39, 2.83, and 1.96 eV for LiGaS2, LiGaSe2 and LiGaTe2, respectively. The observed band gaps consider the studied compounds are potential materials for optoelectronic devices. In addition, the optical response of the studied materials has been analyzed in terms of dielectric constants, refraction, absorption, reflectivity and energy loss function. We have also reported the thermoelectric properties like Seebeck coefficient, thermal and electrical conductivities, and figure of merit as function of temperatures by using BoltzTrap code. The high thermal efficiency and absorption spectra in the visible region make the studied materials multifunctional for energy applications.

SESSION 6 - UTILIZATION OF WASTE RESOURCES : AGRICULTURAL USE OF CITY AND INDUSTRIAL EFFLUENT FOR IRRIGATION : EFFECTS ON SOIL HEALTH AND PLANT QUALITY

( M . Qadir,A . Ghafoor,G . Murtaza ) 한국토양비료학회 1997 Soil Quality Management and Agro-Ecosystem Health Vol.- No.-

Relativistic Bernstein mode instability

Bashir, M F,Noreen, N,Murtaza, G,Yoon, P H Published jointly by The Institute of Physics and 2014 Plasma physics and controlled fusion Vol.56 No.5

Structural and Morphological Properties of Zn1−xZrxO with Room-Temperature Ferromagnetism and Fabricated by Using the Co-Precipitation Technique

M. Hassan,R. Irfan,S. Riaz,S. Naseem,S. S. Hussain,G. Murtaza 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.5

In this study, ZnO was doped with various concentrations of zirconium (xZr = 0 - 5 mole%), by using the co-precipitation method so as to achieve successful formation of a single-phase diluted magnetic semiconductor. X-Ray diffraction results showed that the crystal structure of Zn1−xZrxO was that of hexagonal wurtzite. The structural properties showed no additional phases at low impurity contents (xZr < 3%); however, impurity peaks belonging to ZrO2 appeared at high impurity contents (xZr 3%). The calculated ZnO lattice constants ‘a’ and ‘c’ were found to be 3.256 °A and 5.203 °A, respectively, which are in close match to the values found in the literature. For undoped ZnO, the average calculated particle size was 75.35 nm, and calculated bond length was 1.98 °A. The residual strains and the secondary phases of ZrO2 were found to affect the lattice parameters and the bond lengths. The scanning electron microscopy images showed a porous structure with non-uniform surface morphology. However, a few nano-scale dendrite-type structures were also present, indicating the potential applications of Zr-doped ZnO in nano-devices. Vibrating sample magnetometry (VSM) was employed to measure the magnetic properties, and the measurements showed undoped ZnO to be diamagnetic; however, doping with Zr induced a small ferromagnetic character at small magnetic fields. On the otherhand, a paramagnetic behavior was evident at higher magnetic fields. The magnetization at 1T was observed to degrade with increasing Zr content in the ZnO host lattice, which was due to the residual strains and the secondary phases.

The study of electronic, elastic, magnetic and optical response of Zn1-xTixY (Y=S, Se) through mBJ potential

Q. Mahmood,M. Hassan,M.A. Faridi,B. Sabir,G. Murtaza,Asif Mahmood 한국물리학회 2016 Current Applied Physics Vol.16 No.5

To explore the structural, electronic, magnetic and optical properties of Zn1-xTixY (Y=S, Se) alloys, in the composition range 0 ≤ x ≤ 1, we have applied full-potential linearized augmented plane wave plus local orbital (FP-LAPW + lo) scheme, which is based on the density functional theory (DFT). Structural optimizations have been done in ferromagnetic (FM) and antiferromagnetic (AFM) phase by using Wu eCohen generalized gradient approximation (WC-GGA), whereas recently developed modified Becke and Johnson (mBJ) potential was employed to study electronic and optical properties. The lower value of ground state energy and negative enthalpy of formation confirm stability in the FM phase. Due to the spin polarization of electrons in the Ti-d orbital, origin of half-metallic ferromagnetism has been expressed by the calculated band structures, electronic density of states (DOS) and magnetic moments. We also have calculated the exchange splitting energy Dx (d), crystal field energy (DEcrystal = Et2g Eeg) and exchange constants (N0a and N0b). The negative value of exchange constant (N0b) and large splitting of 3d-states of Ti show that the down spin potential is more effective than up spin. Finally, the results of optical parameters such as complex dielectric constant ε (u), refractive index n (u), normal incident reflectivity R (u), absorption coefficient ɑ (u), optical conductivity s (u) and optical loss factor L (u) are discussed in the energy range 0e14 eV. Moreover, we have verified the Penn's model by showing the inverse relation between the static dielectric constant and the optical band gap. The direct relation between static dielectric constant and static refractive index has been observed by increasing the composition of Ti. The calculated parameters provide valuable theoretical information for optical and spintronics device applications.

Spatial propagation and damping of ordinary electromagnetic mode

Khokhar, Tajammal H.,Yoon, P. H.,Ló,pez, R. A.,Murtaza, G. American Institute of Physics 2018 Physics of plasmas Vol.25 No.8

Opto-electronic Response of Spinel SiZn2O4to a Modified Becke-Johnson Potential

Manzar Ali,Saleh Mohammad,Hayatullah,Muhammad Haneef,Mahmood Khan,G. Murtaza 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.5

A first-principles technique capable of describing the nearly excited states of semiconductors and insulators, namely the modified Becke-Johnson (mBJ) potential approximation, is used to investigate the electronic band structure and the optical properties of the spinel oxide SiZn2O4. The band gap predicted using the mBJ approximation is significantly more accurate than those previously proposed theoretical works using the common localized density approximation (LDA)and generalized gradient approximation (GGA). Band-gap-dependent optical parameters, like the dielectric constant, index of refraction, reflectivity and optical conductivity, are calculated and analyzed. The result for the dielectric constant shows that the numerical value of the static dielectric constant, after dropping at the steady rate, becomes less than zero, and the material exhibits a metallic behavior. The refractive index also drops below unity for photons higher than 18 eV,which indicates that the velocities of the incident photons are greater than the velocity of light. However, these phenomena can be explained by the fact that a signal must be transmitted as a wave packet rather than a monochromatic wave. This comprehensive theoretical study of the optoelectronic properties predicts that the materials can be used effectively in the optical devices.