Manish K. Kashyap

Effect of substituting sp-element on half metallic ferromagnetism in NiCrSi Heusler alloy

We present a first principle study of new class of high-Tc half-heusler ferromagnets NiCrZ (Z = Si, P, Ge, As, Te). The structure and magnetic properties are investigated through the calculation of the electronic structure, equilibrium lattice constant, magnetic exchange interaction Jij and Curie temperature Tc. The role of sp-elements and the influence of lattice expansion/compression are also studied. In alloys having 20 valence electrons, a pseudo-gap of the majority band can be formed at Fermi level. Otherwise, the half-metallicity and ferromagnetism at temperatures much higher than room temperature are found to be stable in a wide range of lattice expansion. Based on these results, NiCrZ can be expected to be promising materials for spintronics. ∗Electronic address: divan@cmp.sanken.osaka-u.ac.jp.

Effect of oxygen vacancy on half metallicity in Ni-doped CeO2 diluted magnetic semiconductor

The electronic and magnetic properties of Ni-doped CeO2 diluted amgentic semiconductor (DMS) including the effect of oxygen vacancy (Vo) with doping concentration, x = 0.125 have been calculated using FPLAPW method based on Density Functional Theory (DFT) as implemented in WIEN2k. In the present supercell approach, the XC potential was constructed using GGA+U formalism in which Coulomb correction is applied to standard GGA functional within the parameterization of Perdew-Burke-Ernzerhof (PBE). We have found that the ground state properties of bulk CeO2 compound have been modified significantly due to the substitution of Ni-dopant at the cation (Ce) site with/without VO and realized that the ferromagnetism in CeO2 remarkably depends on the Vo concentrations. The presence of Vo, in Ni-doped CeO2, can leads to strong ferromagnetic coupling between the nearest neighboring Ni-ions and induces a HMF in this compound. Such ferromagnetic exchange coupling is mainly attributed to spin splitting of Ni-d states, via...

mBJLDA approach for optical properties of Nowontny-Juza LiMgZ (Z = P, As) compounds

First principles approach has been utilized to investigate electronic and optical properties of LiMgZ (Z = P, As) Newontny-Juza compounds. The exchange and correlation (XC) effects are taken into account by a semi local, orbital independent modified Becke-Johnson (mBJ) potential as coupled with Local Density Approximation (LDA). The local orbital independent mBJ potential could provide better band gap/ HM gap due to its capability to catch the essentials of hybrid functionals. The positive values of real dielectric-function rule out the possibility of showing magnetism by these compounds and stabilize the semiconducting state. The shifting of peaks in optical spectra towards high energy is due to increasing indirect band gap from LiMgP to LiMgAs.

First principle prediction of half metallic ferromagnetism in Heusler NiMnZ (Z = P,Ge) compounds

We present first principle calculations of electronic and magnetic properties of NiMnZ (Z = P,Ge) semi Heusler compounds using full potential linearized augmented plane wave (FPLAPW) method based on density functional theory (DFT). To specify the exchange and correlation (XC) effects, the generalized gradient approximation (GGA) is used. The NiMnP compound is predicted to be exactly half metallic ferromagnet (HMF) of type IA with 100% spin polarization at EF whereas NiMnGe show the low value of spin polarization (51%).

Experimental investigation of plasma instabilities by Fourier analysis in an electron cyclotron resonance ion source

Sarvesh Kumar, Jyotsna Sharma, Prashant Sharma, Shatendra Sharma, Yaduvansh Mathur, Devendra Sharma, and Manish K. Kashyap Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India Amity School of Applied Sciences, Amity University, Gurgaon 122413, Haryana, India USIC, Jawaharlal Nehru University, New Delhi 110067, India Institute for Plasma Research, HBNI, Bhat, Gandhinagar 382428, Gujarat, India Department of Physics, Kurukshetra University, Kurukshetra 136119, Haryana, India

Observation of high magnetocrystalline anisotropy on Co doping in rare earth free Fe2P magnetic material

ab-initio investigation of magnetocrystalline anisotropy energy (MAE) for Fe2P and CoFeP using density functional theory based full-potential linear augmented plane wave (FPLAPW) is reported. CoFeP alloy exhibits large magnetic moment 13.28 µB and enhanced anisotropy energy reaching as high as 1326 µeV/f.u. This energy is nearly doubled as compared to its parent Fe2P alloy, making this system a promising candidate for a rare earth free permanent magnet. Substituitng Co at Fe-3f site in Fe2P helps in stabilizing the new structure and further improves the magnetic properties.ab-initio investigation of magnetocrystalline anisotropy energy (MAE) for Fe2P and CoFeP using density functional theory based full-potential linear augmented plane wave (FPLAPW) is reported. CoFeP alloy exhibits large magnetic moment 13.28 µB and enhanced anisotropy energy reaching as high as 1326 µeV/f.u. This energy is nearly doubled as compared to its parent Fe2P alloy, making this system a promising candidate for a rare earth free permanent magnet. Substituitng Co at Fe-3f site in Fe2P helps in stabilizing the new structure and further improves the magnetic properties.

Investigation of half-metallic ferromagnetism in Ti-doped BeS DMS compound: A promising spintronic material

The first principles calculationshave been performed to calculate the electronic and magnetic properties of Be1-xTixS (x=0.03 and 0.06) Diluted Magnetic Semiconductor (DMS) compound using full potential linearized augmented plane wave (FPLAPW) method based on density functional theory (DFT). The estimatedresults show that the substitution of Ti-dopant at the cation (Be) site alters the ground state properties of host BeS compound significantly and the resultant compounds becomes true half metallic (HM) ferromagnet. This behavior is due to the hybridization of S-p states with Ti-d states at/near EF which introduces a gap in minority spin channel with 100% spin polarization at EF. The resultant compounds at both dopant concentrations have band gap at the Fermi level (EF) for only one spin channel and showing metallic property for other spin channel which is desired feeeature for spintronic applications. The Ti-doping in BeS induces a net magnetic moment of∼2.0 µB which shows an important role played by Ti-d states in total magnetic moment. The half metallic character of Ti-doped BeS makes it as promising material for spintronic devices.The first principles calculationshave been performed to calculate the electronic and magnetic properties of Be1-xTixS (x=0.03 and 0.06) Diluted Magnetic Semiconductor (DMS) compound using full potential linearized augmented plane wave (FPLAPW) method based on density functional theory (DFT). The estimatedresults show that the substitution of Ti-dopant at the cation (Be) site alters the ground state properties of host BeS compound significantly and the resultant compounds becomes true half metallic (HM) ferromagnet. This behavior is due to the hybridization of S-p states with Ti-d states at/near EF which introduces a gap in minority spin channel with 100% spin polarization at EF. The resultant compounds at both dopant concentrations have band gap at the Fermi level (EF) for only one spin channel and showing metallic property for other spin channel which is desired feeeature for spintronic applications. The Ti-doping in BeS induces a net magnetic moment of∼2.0 µB which shows an important role played by Ti-d...

Enhancement of magnetocrystalline anisotropy of MnBi with Co interstitial impurities

A decent value of magnetocrystalline anisotropy energy (MAE) of MnBi increases its chance for being used in permanent magnets and this MAE can easily be enhanced by adding interstitial impurities or dopants. In this direction, to raise MAE and to improve the magnetic properties of MnBi, a full potential report on electronic properties and magnetic response of MnBi containing interstitial Co impurities is presented. A coulomb corrected local density approximation (LDA+U) have been used as exchange-correlational potentials due to presence of strongly correlated Mn-d electrons to calculate ground states properties of present compounds. We have observed that on addition of Co impurities, magnetocrystalline anisotropy constant (K) of MnBi increases from 2.07 MJ/m3 to 3.06 MJ/m3. The magnetic moment is also enhanced further as compared to pristine MnBi. The simulations establish the MnBi with Co impurities as a potential candidate for designing new permanent magnets based on rare-earth free materials.A decent value of magnetocrystalline anisotropy energy (MAE) of MnBi increases its chance for being used in permanent magnets and this MAE can easily be enhanced by adding interstitial impurities or dopants. In this direction, to raise MAE and to improve the magnetic properties of MnBi, a full potential report on electronic properties and magnetic response of MnBi containing interstitial Co impurities is presented. A coulomb corrected local density approximation (LDA+U) have been used as exchange-correlational potentials due to presence of strongly correlated Mn-d electrons to calculate ground states properties of present compounds. We have observed that on addition of Co impurities, magnetocrystalline anisotropy constant (K) of MnBi increases from 2.07 MJ/m3 to 3.06 MJ/m3. The magnetic moment is also enhanced further as compared to pristine MnBi. The simulations establish the MnBi with Co impurities as a potential candidate for designing new permanent magnets based on rare-earth free materials.

Half-Metallic ferromagnetism in V-doped ALP: An imperative compound for spintronics

A supercell approach has been used to performed the ground state calculations of Al1-xVxP (x=0.03) Diluted Magnetic Semiconductor (DMS) compound using full potential linearzed augmented plane wave (FPLAPW) method based on density functional theory (DFT). The calculated properties of bulk InP compound get modified significantly due to the substitution of V-dopant at the cation (Al) site. The new states are produced at EF which accounts for the magnetism on the doping. In V-doped AlP, the hybridization of P-p states with V-d states introduces a gap in minority spin channel with 100% spin polarization at EF. The V-doping in AlP induces a net magnetic moment of ∼2.0 μB which shows an important role played by V-d states in total magnetic moment. The HMF characteristics of V-doped AlP makes it an ideal material for spintronic devices.

A first principles study of half-metallic ferromagnetism in In1-xTixP (x = 0.06) diluted magnetic semiconductor

A first principles approach has been used to calculate the electronic and magnetic properties of In1-xTixP (x = 0.06) diluted magnetic semiconductor (DMS) compound. The calculations have been carried out using the highly precise all electron full potential Linear Augmented Plane Wave (FPLAPW) method within generalized gradient approximation (GGA) as exchange-correlation (XC) potentials. The estimated results show that the Ti-doping generate robust half metallic ferromagnetism with the 100% spin polarization at Fermi level (EF) in InP. Due to this peculiar property, the resultant compound behaves as true half-metallic ferromagnet which is best suited for spintronic applications. The total magnetic moments of this compound are mainly due to Ti-d states present at EF with almost negligible contribution from other atoms.