Formation of the Coulomb gap in a Coulomb glass

Malik, Vikas; Kumar, Deepak

doi:10.1103/physrevb.69.153103

Cited by 21 publications

(15 citation statements)

References 16 publications

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“…For instance, at t = 10 4 s the necessary concentration is equal to 7% and at t = 10 6 s it is 5%. This result for the slow relaxation process might be consistent with the very slow processes evidenced in numerous experiments and reported in previous theoretical studies [9,14,15]. In previous theoretical studies somewhat different time dependences of the SP-DOS g(E, t) at the Fermi energy for T = 0 were predicted.…”

Section: Resultssupporting

confidence: 91%

“…In previous theoretical studies somewhat different time dependences of the SP-DOS g(E, t) at the Fermi energy for T = 0 were predicted. Malik and Kumar [14] found that this dependence fulfills the logarithmic law 1/ ln 2 (ν 0 t), while Yu [9] estimated the SP-DOS at the Fermi level to behave like a logarithmic function 1/ ln(t) or as a power law t −0.05 depending on the initial value of the density of states g(E, 0). It is worth noting that in previous theoretical studies based on the self-consistent equation with the lattice model of the disordered system, the SP-DOS at the Fermi level always decreases with time.…”

Section: Resultsmentioning

confidence: 99%

“…This problem has been addressed by Malik and Kumar [14], who solved analytically the self-consistent equation similar to that used by Yu [9] and who confirmed the general picture of the time relaxation processes for the SP-DOS. One should however note that the self-consistent equation for the SP-DOS used in these studies cannot be rigorously justified.…”

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confidence: 92%

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Simulation of the Coulomb gap evolution in the Coulomb glass

Matulewski¹,

Baranovskiǐ²,

Thomas³

2008

Phys. Status Solidi (c)

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

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Simulation of the Coulomb gap evolution in the Coulomb glass

Matulewski¹,

Baranovskiǐ²,

Thomas³

2008

Phys. Status Solidi (c)

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“…In turn, this seems to imply that many-body effects such as the Orthogonality Catastrophe must play a role in the sluggish dynamics observed in the intrinsic electron-glasses. The interplay between disorder and Coulomb interactions makes Anderson insulators a natural candidate to exhibit out-of-equilibrium transport properties characteristic of glasses [1][2][3][4][5][6][7][8][9][10][11][12]. Glassy features such as slow relaxation, ageing, and other memory effects related to such an electron-glass (EG) scenario have been observed in a number of systems [13].…”

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confidence: 99%

Infrared-Induced Sluggish Dynamics in the GeSbTe Electron Glass

Ovadyahu

2015

Phys. Rev. Lett.

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The electron-glass dynamics of Anderson-localized GeSbTe films is dramatically slowed-down following a brief infrared illumination that increases the system carrier-concentration (and thus its conductance). These results demonstrate that the dynamics exhibited by electron-glasses is more sensitive to carrier-concentration than to disorder. In turn, this seems to imply that many-body effects such as the Orthogonality Catastrophe must play a role in the sluggish dynamics observed in the intrinsic electron-glasses. The interplay between disorder and Coulomb interactions makes Anderson insulators a natural candidate to exhibit out-of-equilibrium transport properties characteristic of glasses [1][2][3][4][5][6][7][8][9][10][11][12]. Glassy features such as slow relaxation, ageing, and other memory effects related to such an electron-glass (EG) scenario have been observed in a number of systems [13]. A feature common to all these systems is relatively high carrier-concentration n. Intrinsic electron-glass effects with relaxation times longer than seconds seem to be peculiar to Anderson insulators with n spanning the range of ≈4x10 19 cm -3 (crystalline indium-oxide) to ≃10 22 cm -3 (beryllium) [13]. The relaxation time τ in amorphous indium-oxide with n<8x10 19 cm -3 dropped by more than two orders of magnitude when n was reduced by a mere factor of ≈three [14]. This is also consistent with the absence of intrinsic EG effects in lightly-doped semiconductors; experiments on phosphorous-doped silicon exhibited relaxation times much shorter than a second [15]. Condensedmatter phenomena that favor high carrier-concentration is usually a many-body effect (screening, superconductivity). It is therefore of interest to study this aspect in a controlled manner. The fast dependence of τ on n observed in [14] employed amorphous indium-oxide samples with different compositions to obtain different carrierconcentrations. The recent observation of coexistence of electron-glass phase with persistent-photoconductivity in GeSb x Te y [16] gives us a unique opportunity to check this issue in a single sample. Persistent-photoconductivity (PPC) is used in this work to change the carrierconcentration of the system by a considerable amount without changing the main structural features of the sample [17]. It is shown that, in the PPC-state, the electronglass dynamics is slowed down by a more than an order of magnitude relative to the dark-state. This dramatic effect may help in elucidating the mechanisms responsible for the slow dynamics exhibited by intrinsic electronglasses as it hints on the importance of many-body effects.Samples used for this study were prepared by e-gun depositing a GeSb 2 Te 5 alloy onto room temperature substrates. The substrates were 0.5µm SiO 2 layer thermally grown on <100> silicon wafers having bulk resistivity ρ ≃ 2x10 -3 Ωcm, deep into the degenerate regime. The wafers were employed as the gate electrode in the field-effect measurements. Polycrystalline samples of GeSb x Te y were obtained by crystalli...

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“…There are two specific phenomena that exhibit sluggish conductance relaxation following excitation by a light-source: persistent-photoconductivity (PPC) that has been studied extensively as of 1968 [1][2][3][4][5][6][7][8][9][10][11][12][13], and the less familiar (but just as controversial) electron-glass [14][15][16][17][18][19][20][21][22][23]. In addition to the similar way these effects are reflected in the sample conductance once triggered by light, both become more prominent at lower temperatures and both exhibit a non-exponential relaxation.…”

Section: Introductionmentioning

confidence: 99%

Coexistence of electron-glass phase and persistent photoconductivity in GeSbTe compounds

Ovadyahu

2015

Phys. Rev. B

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It is demonstrated that persistent-photoconductivity (PPC), well-studied in lightly-doped semiconductors, is observable in GeSbTe compounds using infrared excitation at cryogenic temperatures. The low level of energy-flux necessary to induce an appreciable effect seems surprising given the high carrier-concentration n of these ternary alloys (n>10 20 cm -3 ). On the other hand, their high density of carriers makes GeSbTe films favorable candidates for exhibiting intrinsic electron-glass effects with long relaxation times. These are indeed observed in GeSbTe thin-films that are Anderson-localized. In particular, a memory-dip is observed in samples with sheet resistances larger than ≈105 Ω at T≈4K with similar characteristics as in other systems that exhibit intrinsic electron-glass effects. Persistent-photoconductivity however is observable in GeSbTe films even for sheet resistances of the order of 103 Ω, well below the range of disorder required for observing electron-glass effects. These two non-equilibrium phenomena, PPC and electron-glass, are shown to be of different nature in terms of other aspects as well. In particular, their relaxation dynamics is qualitatively different; the excess conductance ∆G associated with PPC decays with time as a stretched exponential whereas a logarithmic relaxation law characterizes ∆G(t) of all electron-glasses studied to date. Surprisingly, the magnitude of the memory-dip is enhanced when the system is in the PPC state. This counter-intuitive result may be related to the compositional disorder in these materials extending over mesoscopic scales. Evidence in support of this scenario is presented and discussed.

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Formation of the Coulomb gap in a Coulomb glass

Cited by 21 publications

References 16 publications

Simulation of the Coulomb gap evolution in the Coulomb glass

Simulation of the Coulomb gap evolution in the Coulomb glass

Infrared-Induced Sluggish Dynamics in the GeSbTe Electron Glass

Coexistence of electron-glass phase and persistent photoconductivity in GeSbTe compounds

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