Papers by Eronides Da Silva
In this work we study, theoretically, the magnetic properties of transition metals (TMs)-doped Sn... more In this work we study, theoretically, the magnetic properties of transition metals (TMs)-doped SnO2 (with TM = V, Cr, and Mn) in a diluted magnetic oxide configuration, focusing in particular in the role played by the presence of O vacancies, VO, nearby the TM. We present the results of first-principles electronic structure calculations of Sn0.96TM0.04O2 and Sn0.96TM0.04O1.98(VO)0.02 alloys. The calculated total energy
as a function of the total magnetic moment per cell shows a magnetic metastability, corresponding to a high-spin (HS) ground state, respectively, with 2 and 3 mu_B/cell, for Cr and Mn, and a metastable low spin (LS) state, with 0 (Cr) and 1 (Mn) mu_B/cell. For vanadium, only a state with 1 mu_B/cell was found. The spin-crossover energy (ESCO) from the LS to the HS is 114 meV for Cr and 42 meV for Mn. By creating O vacancies close to the TM site, we show that the metastability and ESCO change. For chromium, a new HS state appears (4 mu_B/cell), with an energy barrier of 32 meV relative to the 2 mu_B/cell state. For manganese, the metastable LS state of 1 mu_B/cell disappears, while for vanadium the HS state of 1 mu_B/cell remains. In all cases, the ground state corresponds to the expected HS. These findings suggest that these materials
may be used in applications that require different magnetization states.
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Nanoscale Research Letters, 2011
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Nanoscale Research Letters, 2012
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Journal of Alloys and Compounds, 2002
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Japanese Journal of Applied Physics, 2001
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Process Biochemistry, 2007
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Applied Surface Science, 2008
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Applied Surface Science, 2008
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Quantum Sensing and Nanophotonic Devices II, 2005
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Theoretical Chemistry Accounts, 2010
We report results on the electronic, vibrational, and optical properties of SnO2 obtained using f... more We report results on the electronic, vibrational, and optical properties of SnO2 obtained using first-principles calculations performed within the density functional theory. All the calculated phonon frequencies, real and imaginary parts of complex dielectric function, the energy-loss spectrum, the refractive index, the extinction, and the absorption coefficients show good agreement with experimental results. Based on our calculations, the SnO2 electron and hole effective masses were found to be strongly anisotropic. The lattice contribution to the low-frequency region of the SnO2 dielectric function arising from optical phonons was also determined resulting the values of ɛ 1⊥latt(0) = 14.6 and ɛ 1∥latt(0) = 10.7 for directions perpendicular and parallel to the tetragonal c-axis, respectively. This is in excellent agreement with the available experimental data. After adding the electronic contribution to the lattice contribution, a total average value of ɛ1(0) = 18.2 is predicted for the static permittivity constant of SnO2.
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Semiconductor Science and Technology, 1997
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Materials Science and Engineering: B, 2011
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IEEE Transactions on Nuclear Science, 2000
By introducing small amounts of fluorine into the gate oxide, we have been able to significantly ... more By introducing small amounts of fluorine into the gate oxide, we have been able to significantly alter the radiation response of Metal/SiO2/Si (MOS) capacitors, and their subsequent time dependent behavior. Experimentally we have observed that compared with their control capacitors, which have no fluorine introduced into the oxide, the fluorinated samples exhibit the following major differences: (1) the densities of
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Biosensors and Bioelectronics, 2009
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Papers by Eronides Da Silva
as a function of the total magnetic moment per cell shows a magnetic metastability, corresponding to a high-spin (HS) ground state, respectively, with 2 and 3 mu_B/cell, for Cr and Mn, and a metastable low spin (LS) state, with 0 (Cr) and 1 (Mn) mu_B/cell. For vanadium, only a state with 1 mu_B/cell was found. The spin-crossover energy (ESCO) from the LS to the HS is 114 meV for Cr and 42 meV for Mn. By creating O vacancies close to the TM site, we show that the metastability and ESCO change. For chromium, a new HS state appears (4 mu_B/cell), with an energy barrier of 32 meV relative to the 2 mu_B/cell state. For manganese, the metastable LS state of 1 mu_B/cell disappears, while for vanadium the HS state of 1 mu_B/cell remains. In all cases, the ground state corresponds to the expected HS. These findings suggest that these materials
may be used in applications that require different magnetization states.
as a function of the total magnetic moment per cell shows a magnetic metastability, corresponding to a high-spin (HS) ground state, respectively, with 2 and 3 mu_B/cell, for Cr and Mn, and a metastable low spin (LS) state, with 0 (Cr) and 1 (Mn) mu_B/cell. For vanadium, only a state with 1 mu_B/cell was found. The spin-crossover energy (ESCO) from the LS to the HS is 114 meV for Cr and 42 meV for Mn. By creating O vacancies close to the TM site, we show that the metastability and ESCO change. For chromium, a new HS state appears (4 mu_B/cell), with an energy barrier of 32 meV relative to the 2 mu_B/cell state. For manganese, the metastable LS state of 1 mu_B/cell disappears, while for vanadium the HS state of 1 mu_B/cell remains. In all cases, the ground state corresponds to the expected HS. These findings suggest that these materials
may be used in applications that require different magnetization states.