Spin-dependent tunneling characteristics in Fe/MgO/Fe trilayers: First-principles calculations

Ravan, Bahram Abedi; Shokri, Aliasghar; Yazdani, Ahmad

doi:10.1016/j.ssc.2009.10.040

Cited by 22 publications

(6 citation statements)

References 29 publications

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“…Such applications are essentially based on the large tunneling magnetoresistance (TMR) effect in Fe/MgO multilayer systems. A substantial fraction of previous research is therefore devoted to the electronic transport characteristics of Fe/MgO/Fe(001) trilayer tunnel junctions [7][8][9][10][11][12][13][14][15][16][17] . One major outcome in the importance of these studies is the relevance of resonant interface states for the spin-dependent transport 7 .…”

Section: Introductionmentioning

confidence: 99%

Interface-related magnetic and vibrational properties in Fe/MgO heterostructures from nuclear resonant spectroscopy and first-principles calculations

Eggert

Gruner

Ollefs

et al. 2020

Phys. Rev. Materials

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We combine 57 Fe MÃűssbauer spectroscopy and 57 Fe nuclear resonant inelastic x-ray scattering (NRIXS) in nanoscale polycrystalline [bcc-57 Fe/MgO] multilayers with various Fe layer thicknesses and layer-resolved density-functional-theory (DFT) based first-principles calculations of a (001)-oriented [Fe(8 ML)/MgO(8 ML)](001) heterostructure to unravel the interface-related atomic vibrational properties of a multilayer system. In theory and experiment, we observe consistently enhanced hyperfine magnetic fields compared to bulk which is associated with the Fe/MgO interface layers. NRIXS and DFT both reveal a strong reduction of the longitudinal acoustic (LA) phonon peak in combination with an enhancement of the low-energy vibrational density of states (VDOS) suggesting that the presence of interfaces and the associated increase in the layer-resolved magnetic moments results in drastic changes in the Fe-partial VDOS. From the experimental and calculated VDOS, vibrational thermodynamic properties have been determined as a function of Fe thickness and were found to be in excellent agreement. arXiv:1911.05666v2 [cond-mat.mtrl-sci] 30 Jan 2020

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Section: Introductionmentioning

confidence: 99%

Interface-related magnetic and vibrational properties in Fe/MgO heterostructures from nuclear resonant spectroscopy and first-principles calculations

Eggert

Gruner

Ollefs

et al. 2020

Phys. Rev. Materials

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“…In the present work, we will concentrate on a system consisting of a metallic part and a wide band-gap semiconductor or insulator. We have selected the paradigmatic system Fe/MgO(001), for which the electronic and transport properties have been intensively studied in the past [34][35][36][37][38][39][40][41][42][43][44] due to its relevance for spintronics applications as a tunneling magnetoresistive element in hard disk read heads 45,46 or spin diode or rectifier for magnetic logic elements. 47 The choice of the system was also motivated by recent optical-pump, Xray-probe experiments, where the optical pump pulse was designed to excite the metallic subsystem, only.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of optical excitations in a Fe/MgO(001) heterostructure from time-dependent density functional theory

Gruner

2019

Phys. Rev. B

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In the framework of real-time time-dependent density functional theory (RT-TDDFT) we unravel the layer-resolved dynamics of excited carriers in a (Fe)1/(MgO)3(001) multilayer after an optical excitation with a frequency below the band gap of bulk MgO. Substantial transient changes to the electronic structure, which persist after the duration of the pulse, are mainly observed for inplane polarized electric fields, corresponding to a laser pulse arriving perpendicular to the interface. While the strongest charge redistribution takes place in the Fe layer, a time-dependent change in the occupation numbers is visible in all layers, mediated by the presence of interface states. The time evolution of the layer-resolved time-dependent occupation numbers indicates a strong orbital dependence with the depletion from in-plane orbitals (e. g., d x 2 −y 2 of Fe) and accumulation in outof-plane orbitals (d 3z 2 −r 2 of Fe and pz of apical oxygen). We also observe a small net charge transfer away from oxygen towards the Mg sites even for MgO layers which are not directly in contact with the metallic Fe. arXiv:1901.11513v2 [cond-mat.mtrl-sci]

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“…Understanding the interaction of laser pulses with a heterostructure offers the possibility to induce selectively excitations in a particular layer which may propagate into the entire system. At the interface between metallic and insulating layers, the electronic structure is characterized by the hybridization between orbitals of the metallic and insulating part, which usually leads to localized states within the gap in the adjacent layer of the insulator [36,[39][40][41]. As we will show, these interface states might be employed by a proper choice of the photon energy to foster a simultaneous, concerted excitation of electrons and holes.…”

Section: Introductionmentioning

confidence: 85%

“…Fe/MgO(001) represents the ideal model system to explore such effects. The Fe/MgO system was extensively investigated in the context of TMR (tunnel mag- netoresistance) and benefits from the fact that electronic, magnetic and transport properties are well established [40,41,[43][44][45][46][47][48][49][50]. Recently, also optical and lattice excitations have been subject to theoretical and experimental studies [36,42,51,52].…”

Section: Introductionmentioning

confidence: 99%

Anisotropic carrier dynamics in a laser-excited Fe$_{1}$/(MgO)$_{3}$(001) heterostructure from real-time time-dependent DFT

Shomali,

Gruner,

Pentcheva

2022

Preprint

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The interaction of a femtosecond optical pulse with a Fe1/(MgO)3(001) metal/oxide heterostructure is investigated using time-dependent density functional theory (TDDFT) calculations in the real-time domain. We systematically study electronic excitations as a function of laser frequency, peak power density and polarization direction. While spin-orbit coupling is found to result in only a small time-dependent reduction of magnetization (less than 10 %), we find a marked anisotropy in the response to in-plane and out-of-plane polarized light, which changes its character qualitatively depending on the excitation energy: the Fe-layer is efficiently addressed at low frequencies by in-plane polarized light, whereas for frequencies higher than the MgO band gap, we find a particularly strong response of the central MgO-layer for cross-plane polarized light. For laser excitations between the charge transfer gap and the MgO band gap, the interface plays the most important role, as it mediates concerted transitions from the valence band of MgO into the 3d states of Fe closely above the Fermi level and from the Fe-states below the Fermi level into the conduction band of MgO. As these transitions can occur simultaneously altering charge balance of the layers, they could potentially lead to an efficient transfer of excited carriers into the MgO bulk, where the corresponding electron and hole states can be separated by an energy which is significantly larger than the photon energy.

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Spin-dependent tunneling characteristics in Fe/MgO/Fe trilayers: First-principles calculations

Cited by 22 publications

References 29 publications

Interface-related magnetic and vibrational properties in Fe/MgO heterostructures from nuclear resonant spectroscopy and first-principles calculations

Interface-related magnetic and vibrational properties in Fe/MgO heterostructures from nuclear resonant spectroscopy and first-principles calculations

Dynamics of optical excitations in a Fe/MgO(001) heterostructure from time-dependent density functional theory

Anisotropic carrier dynamics in a laser-excited Fe$_{1}$/(MgO)$_{3}$(001) heterostructure from real-time time-dependent DFT

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