Structural origins of electronic conduction in amorphous copper-doped alumina

Subedi, Kashi N.; Prasai, K.; Kozicki, Michael; Drabold, D. A.

doi:10.1103/physrevmaterials.3.065605

Cited by 14 publications

(11 citation statements)

References 48 publications

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“…

ξ_{i j}^{α} (x) \equiv ψ_{i}^{*} (x) p^{α} ψ_{j} (x)

is a complex‐valued function,

ψ_{i} (x)

is the

i th

Kohn–Sham eigenfunction, and

p^{α} = \frac{ℏ}{i} \frac{\partial}{\partial {boldx}_{α}}, (α = x, y, z)

. We have used this approach to successfully describe transport in a solid electrolyte material, [ 43 ] Cu‐doped a‐alumina, [ 44 ] and Cu‐doped tantala. [ 45 ]…”

Section: Resultsmentioning

confidence: 99%

“…ξ α ij ðxÞ ≡ ψ Ã i ðxÞp α ψ j ðxÞ is a complex-valued function, ψ i ðxÞ is the ith Kohn-Sham eigenfunction, and p α ¼ ℏ i ∂ ∂x α , ðα ¼ x, y, zÞ. We have used this approach to successfully describe transport in a solid electrolyte material, [43] Cu-doped a-alumina, [44] and Cu-doped tantala. [45] The SPC for FEAR-I model is visualized as a grayscale plot in Figure 7.…”

Section: Space-projected Conductivitymentioning

confidence: 99%

See 1 more Smart Citation

Forced Enhanced Atomic Refinement Modeling of the Metallic Glass Cu₄₆Zr₄₆Al₈

Thapa

Subedi

Bhattarai

et al. 2021

Physica Status Solidi (b)

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Herein, the structure of Cu46Zr46Al8 is inverted from X‐ray structure factor data and energy minimizations as implemented with forced enhanced atomic refinement (FEAR). The models generated are in good agreement with structural data obtained from diffraction experiment. Voronoi tessellation analysis shows reasonable agreement with previous results, and the models include structural units believed to have slow dynamics near glass transition and be responsible for the excellent glass forming ability of this metallic glass. It is shown, with constant temperature molecular dynamics (MD), that there is a significant increase in the fraction of these particular clusters near the glass transition. Space‐projected conductivity (SPC) calculations show that conduction through Zr dominates over Cu. Vibrational modes are strongly localized on a few Al atoms at high frequencies and distributed almost uniformly on Cu and Zr atoms at low frequencies.

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“…

ξ_{i j}^{α} (x) \equiv ψ_{i}^{*} (x) p^{α} ψ_{j} (x)

is a complex‐valued function,

ψ_{i} (x)

is the

i th

Kohn–Sham eigenfunction, and

p^{α} = \frac{ℏ}{i} \frac{\partial}{\partial {boldx}_{α}}, (α = x, y, z)

. We have used this approach to successfully describe transport in a solid electrolyte material, [ 43 ] Cu‐doped a‐alumina, [ 44 ] and Cu‐doped tantala. [ 45 ]…”

Section: Resultsmentioning

confidence: 99%

Section: Space-projected Conductivitymentioning

confidence: 99%

Forced Enhanced Atomic Refinement Modeling of the Metallic Glass Cu₄₆Zr₄₆Al₈

Thapa

Subedi

Bhattarai

et al. 2021

Physica Status Solidi (b)

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show abstract

“…In our previous works, we studied conduction mechanisms in few resistive memory materials, namely, a‐

{Al}_{2} {normalO}_{3} : Cu

[ 7,28 ] and a‐

{Ta}_{2} {normalO}_{5} : Cu

. [ 29 ] In both cases, we find that the Cu atoms segregate and form a cluster‐like structure in the highly ionic host.…”

Section: Discussionmentioning

confidence: 99%

“…[26] We have provided insight into this elsewhere. [7,[26][27][28][29] Another example of keen current interest is physical unclonable function (PUF) devices for computer security, made from a-Si suboxide materials, as we discuss on more detail in Section 6.4. Another example of interest is conductance fluctuation in amorphous systems.…”

Section: Computing Spatial Information About Transportmentioning

confidence: 99%

Space‐Projected Conductivity and Spectral Properties of the Conduction Matrix

Subedi

Prasai

Drabold

2020

Physica Status Solidi (b)

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Herein, the Kubo–Greenwood formula is utilized to project the electronic conductivity into real space, and a Hermitian positive semidefinite matrix Γ is discussed, which is called the conduction matrix, that reduces the computation of spatial conduction activity to a diagonalization. It is shown that for low‐density amorphous carbon, connected sp2 rings and sp chains are conduction‐active sites in the network. In amorphous silicon, transport involves hopping through tail states mediated by the defects near the Fermi level. It is found that for liquid silicon, thermal fluctuations induce spatial and temporal conductivity fluctuations in the material. The frequency‐dependent absorption of light as a function of wavelength in an amorphous silicon suboxide (a‐SiO1.3) is also studied. It is shown that the absorption is strongly frequency dependent and selects out different oxygen vacancy subnetworks depending on the frequency. Γ is diagonalized to obtain conduction eigenvalues and eigenvectors, and it is shown that the density of states of the eigenvalues for FCC aluminum has an extended spectral tail that distinguishes metals from insulators and semiconductors. The method is easy to implement with any electronic structure code, providing suitable estimates for single‐particle electronic states and energies.

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“…We have used this approach to describe transport in a solid electrolyte material 1 and Cu -doped a-alumina 32 . In a mixed (insulating/conducting) system like ours only a few eigenvectors of Γ characterize essentially all conduction in the system.…”

Section: Space Projected Conductivitymentioning

confidence: 99%

Structure and charge transport of amorphous $Cu$-doped $Ta_2O_5$ : An ab initio study

Thapa,

Bhattarai,

Kozicki

et al. 2020

Preprint

Self Cite

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In this paper, we present ab initio computer models of Cu -doped amorphous T a2O5 , a promising candidate for Conducting Bridge Random Access Memory (CBRAM) memory devices, and study the structural, electronic, charge transport and vibrational properties based on plane-wave density functional methods. We offer an atomistic picture of the process of phase segregation/separation between Cu and T a2O5 subnetworks. Electronic calculations show that the models are conducting with extended Kohn-Sham orbitals around the Fermi level. In addition to that, we also characterize the electronic transport using the Kubo-Greenwood formula modified suitably to calculate the space-projected conductivity (SPC) 1 . Our SPC calculations show that Cu clusters and under-coordinated T a adjoining the Cu are the conduction-active parts of the network. We also report information about the dependence of the electrical conductivity on the connectivity of the Cu submatrix. Vibrational calculations for one of the models has been undertaken with an emphasis on localization and animation of representative modes.

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Structural origins of electronic conduction in amorphous copper-doped alumina

Cited by 14 publications

References 48 publications

Forced Enhanced Atomic Refinement Modeling of the Metallic Glass Cu₄₆Zr₄₆Al₈

Forced Enhanced Atomic Refinement Modeling of the Metallic Glass Cu₄₆Zr₄₆Al₈

Space‐Projected Conductivity and Spectral Properties of the Conduction Matrix

Structure and charge transport of amorphous $Cu$-doped $Ta_2O_5$ : An ab initio study

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Structural origins of electronic conduction in amorphous copper-doped alumina

Cited by 14 publications

References 48 publications

Forced Enhanced Atomic Refinement Modeling of the Metallic Glass Cu46Zr46Al8

Forced Enhanced Atomic Refinement Modeling of the Metallic Glass Cu46Zr46Al8

Space‐Projected Conductivity and Spectral Properties of the Conduction Matrix

Structure and charge transport of amorphous $Cu$-doped $Ta_2O_5$ : An ab initio study

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Product

Resources

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Forced Enhanced Atomic Refinement Modeling of the Metallic Glass Cu₄₆Zr₄₆Al₈

Forced Enhanced Atomic Refinement Modeling of the Metallic Glass Cu₄₆Zr₄₆Al₈