| 1. |
- Miller, Casey W., et al.
(författare)
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Dynamic spin-polarized resonant tunneling in magnetic tunnel junctions
- 2007
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 99:4
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Tidskriftsartikel (refereegranskat)abstract
- Precisely engineered tunnel junctions exhibit a long sought effect that occurs when the energy of the electron is comparable to the potential energy of the tunneling barrier. The resistance of metal-insulator-metal tunnel junctions oscillates with an applied voltage when electrons that tunnel directly into the barrier's conduction band interfere upon reflection at the classical turning points: the insulator-metal interface and the dynamic point where the incident electron energy equals the potential barrier inside the insulator. A model of tunneling between free electron bands using the exact solution of the Schrodinger equation for a trapezoidal tunnel barrier qualitatively agrees with experiment.
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| 2. |
- Miller, Casey W., et al.
(författare)
-
Impact of interfacial roughness on tunneling conductance and extracted barrier parameters
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:4
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Tidskriftsartikel (refereegranskat)abstract
- The net tunneling conductance of metal-insulator-metal tunnel junctions is studied using a distribution of barrier thicknesses consistent with interfacial roughness typical of state-of-the-art tunnel junctions. Moderate amounts of roughness cause the conductance to resemble that of much thinner and taller barriers. Fitting numerically generated conductance data that include roughness with models that assume a single-thickness barrier leads to erroneous results for both the barrier height and width. Rules of thumb are given that connect the roughness to the real space mean thickness and the thickness inferred from fitting the net conductance with traditional tunneling models.
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| 3. |
- Miller, Casey W., et al.
(författare)
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Origin of the breakdown of Wentzel-Kramers-Brillouin-based tunneling models
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:21
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Tidskriftsartikel (refereegranskat)abstract
- The tunneling conductance of three varieties of CoFeB/MgO/CoFeB magnetic tunnel junctions depends quadratically on the applied voltage to anomalously high biases. Within the framework traditional of WKB models, this implies unphysical tunnel barrier parameters: heights near 20 eV, or widths corresponding to fewer than two MgO lattice constants. We demonstrate that the failure of such models to yield physically reasonable parameters originates from an experimentally unavoidable distribution of barrier thicknesses, possibly acting synergistically with the band structure of the barrier material. This implies that existing WKB models may lead to physically incorrect barrier parameters for contemporary tunnel junctions, magnetic or otherwise.
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| 4. |
- Miller, Casey W., et al.
(författare)
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Temperature and angular dependences of dynamic spin-polarized resonant tunneling in CoFeB/MgO/NiFe junctions
- 2008
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 103:7, s. 07A904-
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Tidskriftsartikel (refereegranskat)abstract
- The bias dependence of tunneling magnetoresistance oscillations due to dynamic resonant tunneling in CoFeB/MgO/NiFe magnetic tunnel junctions was studied as functions of temperature and the relative magnetization angle of the two magnetic layers. The effect of temperature is consistent with thermal smearing, while that of the relative magnetic orientation was typical of a spin valve. A model of tunneling between spin-split free electron bands using the exact solution of the Schrodinger equation for a trapezoidal tunnel barrier agrees with experiment, underscoring the simplicity of dynamic resonant tunneling.
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| 5. |
- Thees, Maximilian, et al.
(författare)
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Imaging the itinerant-to-localized transmutation of electrons across the metal-to-insulator transition in V2O3
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:45
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Tidskriftsartikel (refereegranskat)abstract
- In solids, strong repulsion between electrons can inhibit their movement and result in a “Mott” metal-to-insulator transition (MIT), a fundamental phenomenon whose understanding has remained a challenge for over 50 years. A key issue is how the wave-like itinerant electrons change into a localized-like state due to increased interactions. However, observing the MIT in terms of the energy- and momentum-resolved electronic structure of the system, the only direct way to probe both itinerant and localized states, has been elusive. Here we show, using angle-resolved photoemission spectroscopy (ARPES), that in V2O3, the temperature-induced MIT is characterized by the progressive disappearance of its itinerant conduction band, without any change in its energy-momentum dispersion, and the simultaneous shift to larger binding energies of a quasi-localized state initially located near the Fermi level.
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