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- 1. J.Am.Chem.Soc. 130, 48 (2008) , ACS , “Enhanced Ferromagnetism and Tunable Saturation Magnetization of Mn/C Codoped GaN Nanostructures Synthesized by Carbothermal Nitridation”, Zeyan Wang, Baibiao Huang, Lin Yu, Ying Dai, Peng Wang, Xiaoyan Qin, Xiaoyang Zhang, Jiyong Wei, Jie Zhan, Xiangyang Jing, Haixia Liu, and Myung-Hwan WhangboMn/C-codoped GaN nanostructures were synthesized by carbothermal nitridation with active charcoal as the carbon source. Nanostructures such as zigzag nanowires and nanoscrews were observed by varying the reaction time and the C/Ga molar ratio of the starting material used for the synthesis. The structures and morphologies of the as-grown samples were characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy measurements. The doping of both Mn and C in the GaN matrix was confirmed by X-ray photoelectron spectroscopy measurements, and the ferromagnetic properties of Mn/C-codoped GaN samples were confirmed by room-temperature magnetization measurements. The saturation magnetization of Mn/C-codoped GaN increases steadily with increasing C/Ga molar ratio of the starting material at a rate of ~0.023 emu/g per C/Ga molar ratio, and the ferromagnetism of Mn/C-codoped GaN can be stronger than that of Mn-doped GaN by a factor of ~40. A plausible growth mechanism was proposed, and the role of carbon codoping in tuning the morphology and ferromagnetic property was discussed. Our work suggests that carbon doping in the GaN matrix favors the N sites over the Ga sites, Mn/C-codoping in the GaN matrix is energetically favorable, and the C-codoping strongly enhances the preference of the FM coupling to the AFM coupling between the two doped Mn sites. These suggestions were probed on the basis of first-principles density functional theory electronic structure calculations for a number of model doped structures constructed with a 32-atom 2 × 2 × 2 supercell. (Read more)
- 2. J. Appl. Phys. 101, 013902 (2007) , “An electron paramagnetic resonance study of n-type Zn1−xMnxO: A diluted magnetic semiconductor”, A. Ben Mahmoud, H. J. von Bardeleben, J. L. Cantin, E. Chikoidze, and A. MaugerWe present the results of an electron paramagnetic resonance study of homogeneous single phase Zn1−xMnxO thin films with Mn concentrations varying between x=0.07 and x=0.34. Our results show antiferromagnetic (AF) coupling in the entire... (Read more)
- 3. Phys. Rev. B 75, 195335 (2007) , “Computational and experimental imaging of Mn defects on GaAs (110) cross-sectional surfaces”, A. Stroppa, X. Duan, M. Peressi, D. Furlanetto, and S. ModestiWe present a combined experimental and computational study of the (110) cross-sectional surface of Mn δ-doped GaAs samples. We focus our study on three different selected Mn defect configurations not previously studied in detail, namely surface interstitial Mn, isolated and in pairs, and... (Read more)
- 4. Phys. Rev. B 75, 115113 (2007) , “Structural, electronic, and magnetic properties of Mn-doped Ge nanowires by ab initio calculations”, J. T. Arantes, Antônio J. R. da Silva, and A. FazzioUsing ab initio total energy density-functional theory calculations, we investigated the electronic, structural, and magnetic properties of manganese-doped germanium nanowires. The nanowires have been constructed along the [110] direction and the dangling bonds on the surface have been... (Read more)
- 5. Phys. Rev. B 75, 115111 (2007) , “Spin dynamics in a weakly itinerant magnet from 29Si NMR in MnSi”, M. Corti, F. Carbone, M. Filibian, Th. Jarlborg, A. A. Nugroho, and P. Carretta29Si NMR spectra and nuclear spin-lattice relaxation rate measurements in MnSi paramagnetic phase are presented. The experimental results are analyzed in the framework of the self-consistent renormalization theory for spin fluctuations, and detailed estimates of microscopic parameters... (Read more)
- 6. Phys. Rev. B 75, 113310 (2007) , “Hole spin polarization in GaAs:Mn/AlAs multiple quantum wells”, V. F. Sapega, O. Brandt, M. Ramsteiner, K. H. Ploog, I. E. Panaiotti, and N. S. AverkievWe study the effect of confinement on the spin polarization of holes bound to Mn acceptors in paramagnetic GaAs:Mn/AlAs multiple quantum wells. It is demonstrated that the polarization of these bound holes is governed by the properties of the host material rather than by quantum confinement. The... (Read more)
- 7. Phys. Rev. B 75, 113201 (2007) , “Local structure around Mn atoms in Si crystals implanted with Mn+ studied using x-ray absorption spectroscopy techniques”, A. Wolska, K. Lawniczak-Jablonska, M. Klepka, M. S. Walczak, and A. MisiukThe local order around Mn atoms in the Mn-implanted Si samples, with ferromagnetic properties, has been investigated by use of x-ray-absorption spectroscopy techniques. Analysis of both extended x-ray-absorption fine structure and x-ray absorption near-edge structure spectra clearly indicates that... (Read more)
- 8. Phys. Rev. B 75, 085203 (2007) , “Structural and magnetic properties of Mn-implanted Si”, Shengqiang Zhou, K. Potzger, Gufei Zhang, A. Mücklich, F. Eichhorn, N. Schell, R. Grötzschel, B. Schmidt, W. Skorupa, M. Helm, J. Fassbender, and D. GeigerStructural and magnetic properties in Mn-implanted, p-type Si were investigated. High resolution structural analysis techniques such as synchrotron x-ray diffraction revealed the formation of MnSi1.7 nanoparticles already in the as-implanted samples. Depending on the Mn fluence,... (Read more)
- 9. Phys. Rev. B 75, 075316 (2007) , “Theoretical investigation of a Mn-doped Si/Ge heterostructure”, J. T. Arantes, Antônio J. R. da Silva, A. Fazzio, and A. AntonelliWe investigate, through ab initio density-functional theory calculations, the electronic and structural properties of neutral Mn impurities at tetrahedral interstitial and substitutional sites in both Si and Ge layers of a Si/Ge heterostructure. We conclude that substitutional Mn at the Ge... (Read more)
- 10. Phys. Rev. B 75, 035322 (2007) , “Ab initio study of electronic and magnetic properties of the C-codoped Ga1−xMnxN (100) surface”, Q. Wang, Q. Sun, and P. JenaFirst principles calculations based on gradient corrected density functional theory have been carried out to study the magnetic coupling between Mn atoms in pure and carbon doped Ga1−xMnxN thin films. We show that the ground state of Mn-doped GaN (100) thin... (Read more)
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