Hardening of the Coulomb gap by electronic polarons

Chicon, R.; Ortuño, M.; Pollak, M.

doi:10.1103/physrevb.37.10520

Cited by 29 publications

(14 citation statements)

References 8 publications

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“…The temperature dependence of the resistance shows a crossover from hopping to activation mechanism at low temperatures, implying that the DOS vanishes for MnPbS. Yet, an external magnetic field reverts this behavior, suggesting spin-spin correlation rather than charge-charge correlation between electrons is responsible for the HG formation 5 7 . The VRH behavior above the crossover temperature suggests the hopping transport of BMP in the doped samples.…”

Section: Discussionmentioning

confidence: 94%

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Magnetic hard gap due to bound magnetic polarons in the localized regime

Rimal

Tang

2017

Sci Rep

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We investigate the low temperature electron transport properties of manganese doped lead sulfide films. The system shows variable range hopping at low temperatures that crosses over into an activation regime at even lower temperatures. This crossover is destroyed by an applied magnetic field which suggests a magnetic origin of the hard gap, associated with bound magnetic polarons. Even though the gap forms around the superconducting transition temperature of lead, we do not find evidence of this being due to insulator-superconductor transition. Comparison with undoped PbS films, which do not show the activated transport behavior, suggests that bound magnetic polarons create the hard gap in the system that can be closed by magnetic fields.

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Section: Discussionmentioning

confidence: 94%

“…Several possible mechanisms may be responsible to the HG formation. Electronic (lattice) polarons can result in the HG at low temperature 5 6 . HGs may also be of magnetic origins associated with the exchange coupling as found in Mn doped CdTe and B doped Si 7 8 .…”

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confidence: 99%

Magnetic hard gap due to bound magnetic polarons in the localized regime

Rimal

Tang

2017

Sci Rep

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“…As for the hard gap energy E H , it can be regarded as a constant in spite of its various origins. 4,7,10 Taking into account the interactions mentioned above, the total energy difference between the initial occupied i state and the final vacant j state of the hopping process in the distance r is…”

Section: Theoretical Model Of Electrical Transportmentioning

confidence: 99%

“…Various electrical transport phenomena in disordered systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] have been extensively studied due to the significant importance not only in fundamental physics but also in technological applications. Assuming that the density of state is a constant near the Fermi energy, the variable range hopping resistance, 1 ϰ exp͓͑T M / T͒ 1/4 ͔, was predicted by Mott for the disordered systems without Coulomb interaction.…”

Section: Introductionmentioning

confidence: 99%

“…12͒ and insulating Si:B, 7 the hard gap energy was believed to originate from spin-spin exchange interaction after spin-glass ordering. In amorphous In/ InO x films, the hard gap was interpreted in terms of electric polaron excitations 3,10 due to many-electron interactions. In dilute magnetic material Cd 1−x Mn x Te: In, the hard gap was explained by the formation of magnetic polarons.…”

Section: Introductionmentioning

confidence: 99%

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Transformation of electrical transport from variable range hopping to hard gap resistance in Zn1−xFexO1−v magnetic semiconductor films

Tian

Shen

Zhang

et al. 2006

Journal of Applied Physics

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Transformation of the electrical transport from the Efros and Shklovskii ͓J. Phys. C 8, L49 ͑1975͔͒ variable range hopping to the "hard gap" resistance was experimentally observed in a low temperature range as the Fe compositions in Zn 1−x Fe x O 1−v ferromagnetic semiconductor films increase. A universal form of the resistance versus temperature, i.e., ϰ exp͓T H / T + ͑T ES / T͒ 1/2 ͔, was theoretically established to describe the experimental transport phenomena by taking into account the electron-electron Coulomb interaction, spin-spin exchange interaction, and hard gap energy. The spin polarization ratio, hard gap energy, and ratio of exchange interaction to Coulomb interaction were obtained by fitting the theoretical model to the experimental results. Moreover, the experimental magnetoresistance was also explained by the electrical transport model.

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