Concept of resonances in disordered metallic matter

Nowak, Hans; Häußler, P.

doi:10.1016/s0022-3093(99)00269-0

Cited by 23 publications

(12 citation statements)

References 7 publications

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“…The enhanced contributions in the amorphous case at lower energies are taken as indications of the shift by the limited mass. c) The regions around K pe=2kF=Qpe where the electronic system, the static structure, and its dynamic excitations are coupled resonantly to each other, forming the spherons [10] For the dynamic excitations (Fig. 2b) we follow the same construction.…”

Section: Structural Features Of Disordered Systemsmentioning

confidence: 99%

“…Calculations of the electrical resistivity and the thermopower, as well as of the electronic contribution to the thermal conductance and the specific heat, taking the spherons into account, gave first indications of their varying influence versus T [6,10,16].…”

Section: Structural Features Of Disordered Systemsmentioning

confidence: 99%

“…Above a characteristic temperature T o , so called spherons exist, describing local spherical-periodic resonances between the dynamic excitations, the static structure, and the electronic system [10]. Spherons can get excited thermally, as well as by scattering effects and may serve as scattering centers.…”

Section: Introductionmentioning

confidence: 99%

“…Spherons can get excited thermally, as well as by scattering effects and may serve as scattering centers. They are claimed to be responsible for many anomalies at low and medium temperatures [10]. Strong inelastic umklapp scattering effects, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…of the itinerant electrons, will occur as soon as the temperature is higher than T o . Effects have already been shown for electronic transport properties [5,10] but, may also exist for dynamic excitations in dielectric glasses.…”

Section: Introductionmentioning

confidence: 99%

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Analogies and differences between the crystalline and the disordered state

Häußler

2004

phys. stat. sol. (c)

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We report on a general feature of liquid and amorphous systems (metals, ionic systems, semiconductors), namely the spherical periodicity of nearest-neighbour shell distances and its influence on several properties. The electronic states as well as the dynamic excitations are influenced by two effects: spherical periodicity creates pseudogaps in their density of states at high energies, and its limited total mass causes low-energy effects. The former are mainly responsible for the stability of the phase and for absolute values of electronic transport properties, the latter for their temperature dependencies. Under particular conditions there is a spherical-periodic resonance between the electronic states, the static structure, as well as its dynamic excitations, which may be described as a new quasiparticle, the so called spheron. Besides its influence on electronic transport properties spherons may also affect dielectric glasses. Whenever there is periodicity in an arrangement of atoms, strong influences arise on electronic states (band-structure effects) as well as on dynamic excitations due to coherent scattering effects. In crystals there are mirror planes and, accordingly, planar electron interferences and planar dynamic excitations (phonons) get formed, both with the same periodicity as the periodic arrangement of the atoms. In liquid and amorphous systems, more in the latter than in the former, over the years it became obvious that there is spatial limited, spherical-periodic order (SPO) around any atom [5]. During phase formation the SPO is caused by a selforganized optimization process of spherical resonances between two subsystems, namely the valence electrons (s+p) in total as the one and the forming static structure as the other one. It is based on characteristic momenta of both subsystems and hence is a global effect. It was recognized that, irrespective of the presence of itinerant electrons, the resonance occurs not only in metallic systems [6], but also in glassy semiconductors and insulators [7], in ionic glasses [8], as well as glassy quasicrystals [5]. Spherical periodicity is the characteristic structural feature of condensed matter at early stages. Correlated with the resonance a gap opens at the Fermi energy E F (Peierls-like) [9]. Due to this gap, electronic transport, up to localization, will strongly depend on the strength of the resonance [5,6]. Differences to the crystalline case arise from the facts that in spatially limited, spherical periodic systems there is only a broad pseudo Bragg peak instead of a sharp one in a crystal, and in addition, there is a limited total mass of the ordered region.

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Section: Structural Features Of Disordered Systemsmentioning

confidence: 99%

Section: Structural Features Of Disordered Systemsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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