Heusler compounds are exciting materials for future spintronics applications because they display... more Heusler compounds are exciting materials for future spintronics applications because they display a wide range of tunable electronic and magnetic interactions. Here, we use a femtosecond laser to directly transfer spin polarization from one element to another in a half-metallic Heusler material, Co2MnGe. This spin transfer initiates as soon as light is incident on the material, demonstrating spatial transfer of angular momentum between neighboring atomic sites on time scales < 10 fs. Using ultrafast high harmonic pulses to simultaneously and independently probe the magnetic state of two elements during laser excitation, we find that the magnetization of Co is enhanced, while that of Mn rapidly quenches. Density functional theory calculations show that the optical excitation directly transfers spin from one magnetic sublattice to another through preferred spin-polarized excitation pathways. This direct manipulation of spins via light provides a path toward spintronic devices that ...
We report a large spin Hall effect in the 3d transition metal alloy NixCu1-x for , detected via t... more We report a large spin Hall effect in the 3d transition metal alloy NixCu1-x for , detected via the ferromagnetic resonance of a Permalloy (Py = Ni80Fe20) film deposited in a bilayer with the alloy. A thickness series at x = 0.6, for which the alloy is paramagnetic at room temperature, allows us to determine the spin Hall ratio , spin diffusion length , spin mixing conductance , and damping due to spin memory loss. We compare our results with similar experiments on Py/Pt bilayers measured using the same method. Ab initio band structure calculations with disorder and spin-orbit coupling suggest an intrinsic spin Hall effect in NixCu1-x alloys, although the experiments here cannot distinguish between extrinsic and intrinsic mechanisms. I.
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2009
... The absorption bands due to AlO 4 or AlO 6 and PbO 4 groups are located in the same position ... more ... The absorption bands due to AlO 4 or AlO 6 and PbO 4 groups are located in the same position as the position of borate groups [17], [18] and [19]. ... These peaks occur near 770, 915, 1020 cm − 1, which can be associated with the vibrations of AlO 4 group [20], [36], [37] and [38]. ...
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2009
The infrared absorption spectra of PbO-Al2O3-B2O3-SiO2 glasses have been measured in the spectral... more The infrared absorption spectra of PbO-Al2O3-B2O3-SiO2 glasses have been measured in the spectral range 600-4000 cm-1 before and after absorbed dose of 50 Gy, 4 kGy and 50 kGy to investigate the structural change due to irradiation. The structural change due to composition has also been discussed. The experimental results clearly indicate that after irradiation, a significant change in structure of lead alumino borosilicate glass network is observed. It was shown that BO4 groups decreases and BO3 groups increases with the increase of Al2O3.
Borate and borosilicate glasses with compositions of xZnO-2xPbO-(1-3x)B2O3 and xZnO-2xPbO-1/2(1-3... more Borate and borosilicate glasses with compositions of xZnO-2xPbO-(1-3x)B2O3 and xZnO-2xPbO-1/2(1-3x)B2O3-1/2(1-3x)SiO2 with x varying from 0.1 to 0.26 mole fraction were prepared by the conventional melt quench technique. Optical and structural properties have been determined by using ultraviolet-visible (UV/vis) and Fourier transform infrared (FTIR) spectroscopic techniques. Decreases in the band gap from 3.57 to 2.62 eV for borate glasses and from 3.00 to 2.35 eV for borosilicate glasses with an increase in the metal oxide content is observed. The density and molar volume has also been measured. Increases in density from 3.994 to 6.339 g cm-3 for borate and from 4.221 to 6.548 g cm-3 for borosilicate glasses are observed with an increase in metal oxide (PbO, ZnO or PbO+ZnO) content. Changes in the atomic structure with composition are observed due to the formation of BO4- units.
The density, molar volume, optical energy bandgap, and infrared absorption spectra in the range 4... more The density, molar volume, optical energy bandgap, and infrared absorption spectra in the range 400-4000 nm of borate glasses with composition 2xLi 2 O-xAl 2 O 3 -͑1-3x͒B 2 O 3 ͑x varying from 0.10 to 0.18 mol fraction͒ prepared by conventional melt quench technique have been measured before and after successive ␥-ray irradiation at the dose of 2.5 K Gy to elucidate the effect of gamma irradiation on such glasses. The radiation induced defects created by ␥-ray and the changes in optical properties have been discussed.
MTJs and increasing interest in STT-MRAM in semiconductor industry have been witnessed in recent ... more MTJs and increasing interest in STT-MRAM in semiconductor industry have been witnessed in recent years. This paper will present a review on the progress in the intrinsic switching current density reduction and STT-MRAM prototype chip demonstration. Challenges to overcome in order for STT-MRAM to be a mainstream memory technology in future technology nodes will be discussed. Finally, potential applications of STT-MRAM in embedded and standalone memory markets will be outlined.
Heusler compounds are exciting materials for future spintronics applications because they display... more Heusler compounds are exciting materials for future spintronics applications because they display a wide range of tunable electronic and magnetic interactions. Here, we use a femtosecond laser to directly transfer spin polarization from one element to another in a half-metallic Heusler material, Co2MnGe. This spin transfer initiates as soon as light is incident on the material, demonstrating spatial transfer of angular momentum between neighboring atomic sites on time scales < 10 fs. Using ultrafast high harmonic pulses to simultaneously and independently probe the magnetic state of two elements during laser excitation, we find that the magnetization of Co is enhanced, while that of Mn rapidly quenches. Density functional theory calculations show that the optical excitation directly transfers spin from one magnetic sublattice to another through preferred spin-polarized excitation pathways. This direct manipulation of spins via light provides a path toward spintronic devices that ...
We report a large spin Hall effect in the 3d transition metal alloy NixCu1-x for , detected via t... more We report a large spin Hall effect in the 3d transition metal alloy NixCu1-x for , detected via the ferromagnetic resonance of a Permalloy (Py = Ni80Fe20) film deposited in a bilayer with the alloy. A thickness series at x = 0.6, for which the alloy is paramagnetic at room temperature, allows us to determine the spin Hall ratio , spin diffusion length , spin mixing conductance , and damping due to spin memory loss. We compare our results with similar experiments on Py/Pt bilayers measured using the same method. Ab initio band structure calculations with disorder and spin-orbit coupling suggest an intrinsic spin Hall effect in NixCu1-x alloys, although the experiments here cannot distinguish between extrinsic and intrinsic mechanisms. I.
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2009
... The absorption bands due to AlO 4 or AlO 6 and PbO 4 groups are located in the same position ... more ... The absorption bands due to AlO 4 or AlO 6 and PbO 4 groups are located in the same position as the position of borate groups [17], [18] and [19]. ... These peaks occur near 770, 915, 1020 cm − 1, which can be associated with the vibrations of AlO 4 group [20], [36], [37] and [38]. ...
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2009
The infrared absorption spectra of PbO-Al2O3-B2O3-SiO2 glasses have been measured in the spectral... more The infrared absorption spectra of PbO-Al2O3-B2O3-SiO2 glasses have been measured in the spectral range 600-4000 cm-1 before and after absorbed dose of 50 Gy, 4 kGy and 50 kGy to investigate the structural change due to irradiation. The structural change due to composition has also been discussed. The experimental results clearly indicate that after irradiation, a significant change in structure of lead alumino borosilicate glass network is observed. It was shown that BO4 groups decreases and BO3 groups increases with the increase of Al2O3.
Borate and borosilicate glasses with compositions of xZnO-2xPbO-(1-3x)B2O3 and xZnO-2xPbO-1/2(1-3... more Borate and borosilicate glasses with compositions of xZnO-2xPbO-(1-3x)B2O3 and xZnO-2xPbO-1/2(1-3x)B2O3-1/2(1-3x)SiO2 with x varying from 0.1 to 0.26 mole fraction were prepared by the conventional melt quench technique. Optical and structural properties have been determined by using ultraviolet-visible (UV/vis) and Fourier transform infrared (FTIR) spectroscopic techniques. Decreases in the band gap from 3.57 to 2.62 eV for borate glasses and from 3.00 to 2.35 eV for borosilicate glasses with an increase in the metal oxide content is observed. The density and molar volume has also been measured. Increases in density from 3.994 to 6.339 g cm-3 for borate and from 4.221 to 6.548 g cm-3 for borosilicate glasses are observed with an increase in metal oxide (PbO, ZnO or PbO+ZnO) content. Changes in the atomic structure with composition are observed due to the formation of BO4- units.
The density, molar volume, optical energy bandgap, and infrared absorption spectra in the range 4... more The density, molar volume, optical energy bandgap, and infrared absorption spectra in the range 400-4000 nm of borate glasses with composition 2xLi 2 O-xAl 2 O 3 -͑1-3x͒B 2 O 3 ͑x varying from 0.10 to 0.18 mol fraction͒ prepared by conventional melt quench technique have been measured before and after successive ␥-ray irradiation at the dose of 2.5 K Gy to elucidate the effect of gamma irradiation on such glasses. The radiation induced defects created by ␥-ray and the changes in optical properties have been discussed.
MTJs and increasing interest in STT-MRAM in semiconductor industry have been witnessed in recent ... more MTJs and increasing interest in STT-MRAM in semiconductor industry have been witnessed in recent years. This paper will present a review on the progress in the intrinsic switching current density reduction and STT-MRAM prototype chip demonstration. Challenges to overcome in order for STT-MRAM to be a mainstream memory technology in future technology nodes will be discussed. Finally, potential applications of STT-MRAM in embedded and standalone memory markets will be outlined.
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Papers by Monika Arora