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The Phonon-Assisted Radiative Recombination of Excitons Confined in InAs Quantum Dashes

100%

Dusanowski Ł., Musiał A., Sęk G., Machnikowski P.

Acta Physica Polonica A

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2013

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vol. 124

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issue 5

813-816

EN

In this report we have investigated theoretically the phonon-assisted recombination process of excitons confined in strongly elongated semiconductor nanostructures, called quantum dashes. Interaction with phonon bath leads to the occurrence of phonon-assisted recombination, which in the case of acoustic phonons is manifested in the optical spectra as a deviation of the homogeneously broadened emission line shape from expected Lorentzian profile via occurrence of the so-called phonon sidebands. Hereby, we have modeled the influence of the quantum dash geometry on this spectral feature proving pronounced suppression of phonon-induced decoherence for strongly elongated nanostructures. Furthermore, the importance of different phonon coupling mechanisms has been evaluated and the spectral diffusion effects, unavoidable in the time-integrated photoluminescence experiments, have been accounted for.

2

Bond-Selective Excitation and Following Displacement of Ge Atoms in GeTe/Sb_{2}Te_{3} Superlattice

80%

Makino K., Tominaga J., Kolobov A., Fons P., Hase M.

Acta Physica Polonica A

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2012

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vol. 121

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issue 2

336-339

EN

Phase change random access memory devices made from chalcogenides compounds, such as Ge_{2}Sb_{2}Te_{5}, have attracted much attention because of their high-speed read-write and low power consumption capabilities. The phase change in Ge_{2}Sb_{2}Te_{5} is thought to be characterized by the displacement of Ge atoms, accompanying relaxation of surrounding Sb and Te atoms. Here we examine a new approach, that is the manipulation of Ge-Te bonds using linearly-polarized femtosecond near-infrared optical pulses. As a result, p-polarized pump pulses are found to be more effective in inducing the precursor of phase change, probably due to the atomic arrangements along the unique axis of the superlattice structure.

3

Thermal Conductivity of Ce₂Ru₃Ga₉ Compound

80%

Falkowski M., Strydom A.

Acta Physica Polonica A

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2015

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vol. 127

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issue 2

240-242

EN

The Ce-based 2:3:9 series of compounds are known for strongly correlated 4f-electron behaviour. Here, we report for the first time a study of the thermal conductivity κ(T) in zero and 9 T magnetic field for Ce₂Ru₃Ga₉ across the temperature range 2 K ≤ T ≤ 300 K. The zero-field temperature dependence of κ(T) exhibits a pronounced maximum, characteristic for metals with large electronic mean free path and towards room temperature κ(T) starts behaving in a manner usually attributed to the enhanced electron-phonon coupling. Based on the Wiedemann-Franz law the electronic and lattice contributions to the thermal conductivity were estimated. In high temperature region a distinct step-like anomaly at T* = 203 K has been observed which signals a putative phase transition, probably of phononic or lattice origin. We furthermore discuss the effect of applied magnetic fields on the thermal transport in Ce₂Ru₃Ga₉.

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3 Acta Physica Polonica A

1 2015

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1 Dusanowski Ł.

1 Falkowski M.

1 Fons P.

1 Hase M.

1 Kolobov A.

1 Machnikowski P.

1 Makino K.

1 Musiał A.

1 Strydom A.

1 Sęk G.

1 Tominaga J.

The Phonon-Assisted Radiative Recombination of Excitons Confined in InAs Quantum Dashes

Bond-Selective Excitation and Following Displacement of Ge Atoms in GeTe/Sb_{2}Te_{3} Superlattice

Thermal Conductivity of Ce₂Ru₃Ga₉ Compound