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Wyświetlanie 1-15 z 23
Tytuł:
Parametric Phonon-Helicon Interaction in Centrosymmetric Crystals with Strain-Dependent Dielectric Constant
Autorzy:
Artemenko, O. L.
Sevruk, B. B.
Powiązania:
https://bibliotekanauki.pl/articles/1945729.pdf
Data publikacji:
1996-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
Opis:
The process of interaction between circularly polarized coherent transverse phonons and slow electrokinetic waves in the centrosymmetric crystal placed in a longitudinal magnetic field and possessing strong strain dependence of the dielectric constant caused by the electrostriction is considered. The cut-off system of equations for the process of nonlinear four-wave interaction in crystal with a quadratic electrostriction corresponding to direct energy conversion from helicon to acoustic wave is derived. The solution is sought for numerically in the vicinity of a synchronism point determined by the intersection of helicon and phonon dispersion curves at different values of semiconductor plasma parameters. The results show the possibility of effective phonon parametric amplification in semiconductor crystal with the electroinduced elastic anisotropy.
Źródło:
Acta Physica Polonica A; 1996, 90, 3; 531-539
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phonon-Assisted Excitation Transfer in Quantum Dot Molecules
Autorzy:
Rozbicki, E.
Machnikowski, P.
Powiązania:
https://bibliotekanauki.pl/articles/2047376.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
73.63.Kv
Opis:
We derive a quantum-kinetic description of phonon-assisted Förster transfer between two coupled quantum dots (a quantum dot molecule). We show that the exciton state decays to the ground state of the quantum dot molecule via a combination of the Rabi rotation and exponential decay. For moderately spaced dots this process takes place on a picosecond timescale.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 197-202
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tunnelling of Direct and Indirect Excitons in Slightly Asymmetric Double Quantum Wells
Autorzy:
Mazurenko, D. A.
Akimov, A. V.
Moskalenko, E. S.
Zhmodikov, A. L.
Kaplyanskii, A. A.
Challis, L. J.
Cheng, T. S.
Foxon, C. T.
Powiązania:
https://bibliotekanauki.pl/articles/1952066.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
63.20.Kr
Opis:
We report the first studies of luminescence spectra from asymmetric double quantum wells of GaAs with widths around 100 Å differing by only one (2.8 Å) or two monolayers. Studies of the position and intensity of the direct and indirect exciton lines suggest the existence of acoustic phonon-assisted tunnelling between exciton states separated by a few meV. At temperatures 10-20 K the electron tunnelling process is fast enough to maintain thermal equilibrium between these direct and indirect excitons which are connected with holes in the same quantum well.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 895-898
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hot Phonons in a Biased Two-Dimensional InGaAs Channel
Autorzy:
Aninkevičius, V.
Liberis, J.
Matulionis, A.
Matulionienė, I.
Powiązania:
https://bibliotekanauki.pl/articles/1818476.pdf
Data publikacji:
2005-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
72.20.Ht
Opis:
Experimental dependence of microwave noise temperature on supplied electric power is used to estimate hot-phonon number in a modulation-doped In_{0.52}Al_{0.48}As/In_{0.53}Ga_{0.47}As/In_{0.7} Ga_{0.3}As/In_{0.52}Al_{0.48}As two-dimensional electron gas channel (n_{2D}=2.3×10^{12} cm^{-2}). The nonequilibrium occupancy of the involved longitudinal optical phonon states exceeds the equilibrium one nearly twice at 2 kV/cm electric field. test
Źródło:
Acta Physica Polonica A; 2005, 107, 2; 304-309
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron-Optical Phonon Coupling in Double-Barrier Quantum Well Structure
Autorzy:
Kaczmarek, E.
Powiązania:
https://bibliotekanauki.pl/articles/1932087.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.40.Gk
63.20.Kr
Opis:
The electron-LO phonon coupling constant for double-barrier quantum well structure was calculated using the Frohlich model of the electron-phonon interaction and assuming coupling of the confined electron with bulk LO phonon mode. Magnitude of the Huang-Rhys factor g and possibility of detecting of phonon replicas in the resonant tunneling current are discussed for GaAs-Al$\text{}_{x}$Ga$\text{}_{1-x}$As and CdTe based structures.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 233-236
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phonon Induced Drag of Charge Carriers in Heterostructures in Magnetic Fields: Limit of Weak Fields
Autorzy:
Jasiukiewicz, Cz.
Lehmann, D.
Paszkiewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1950859.pdf
Data publikacji:
1996-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
73.40.-c
Opis:
The response of a 2D gas of charge carriers of mobility μ in magnetic field B to pulsed phonon beams is considered. Previously we derived a quantum Langevin equation for the centre-of-mass of the carrier gas, which allows us to calculate the time integrated drag current. This formula is studied in the weak magnetic field limit. When the ratio of the cyclotron frequency ω$\text{}_{c}$ to the frequency ω of phonons is small and μB ≪ 1, the general formula coincides with the corresponding expression obtained in the frame of the Boltzmann equation with the collision integral independent of B.
Źródło:
Acta Physica Polonica A; 1996, 90, 4; 829-832
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gd$\text{}^{3+}$ Spin-Phonon Interactions in Rare-Earth Fluoride Crystals
Autorzy:
Paradowski, M. L.
Misiak, L. E.
Powiązania:
https://bibliotekanauki.pl/articles/2035540.pdf
Data publikacji:
2002-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
76.30.Kg
Opis:
The X-band EPR study of Gd$\text{}^{3+}$-doped LaF$\text{}_{3}$, La$\text{}_{0.9}$Ce$\text{}_{0.1}$F$\text{}_{3}$, La$\text{}_{0.9}$Nd$\text{}_{0.1}$F$\text{}_{ }$3, LiYF$\text{}_{4}$ and LiY$\text{}_{0.9}$Yb$\text{}_{0.1}$F$\text{}_{4}$ single crystals in the temperature range 4.2-295 K was carried out in order to investigate the Gd$\text{}^{3+}$ spin-phonon interactions. Spin-Hamiltonian parameters are analysed in the light of the superposition model and the rotational invariance theory for phonon-induced contributions to spin-Hamiltonian parameters. The 4f$\text{}^{7}$ electron-phonon interactions can be described by the Debye model. It is suggested, from the rotational invariance mechanism for phonon-induced contributions to spin-Hamiltonian parameters, that the rotational contributions are much smaller than those from the strain. Temperature-induced distortions of the crystal field, as well as these distortions caused by the La$\text{}^{3+}$/Nd$\text{}^{3+}$ and Y$\text{}^{3+}$/Yb$\text{}^{3+}$ substitutions, influence significantly the 4f$\text{}^{7}$ electron-phonon interactions. The coupling constant K$\text{}_{2}$ of 4f$\text{}^{7}$ electrons to the whole phonon spectrum of the crystal lattice is stronger in the LaF$\text{}_{3}$, La$\text{}_{0.9}$Ce$\text{}_{0.1}$F$\text{}_{3}$, La$\text{}_{0.9}$Nd$\text{}_{0.1}$F$\text{}_{3}$ with larger temperature-induced distortion of the Gd$\text{}^{3+}$ site symmetry than in LiYF$\text{}_{4}$, LiY$\text{}_{0.9}$Yb$\text{}_{0.1}$F$\text{}_{4}$. Our results are compared with those for Gd$\text{}^{3+}$-doped RbCdF$\text{}_{3}$ and PbF$\text{}_{2}$ single crystals.
Źródło:
Acta Physica Polonica A; 2002, 102, 3; 373-384
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Field Dependence of Phonon-Induced Drag Current of 2D Carriers
Autorzy:
Lehmann, D.
Jasiukiewicz, Cz.
Paszkiewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1968318.pdf
Data publikacji:
1997-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
73.40.-c
Opis:
The magnetic field dependence of the drag current induced by beams of acoustic phonons is studied in a 2D gas of carriers, formed in a heterostructure. This drag current is related to the velocity of the center of mass of the gas. The elimination of the degrees of freedom related to the relative motion of the carriers leads to a Langevin equation for the center-of-mass position vector. From this equation one can obtain an expression for the induced current density which depends on carrier density-density correlation functions. An explicit formula for the time-integrated current density is derived taking into account all intra and inter Landau level transitions. Corresponding numerical results are in good agreement with the experimental patterns.
Źródło:
Acta Physica Polonica A; 1997, 92, 5; 891-894
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical and Magnetic Properties of PbTe(Ni)
Autorzy:
Romčević, N.
Trajić, J.
Romčević, M.
Stojanović, D.
Kuznetsova, T.
Khokhlov, D.
Dobrowolski, W.
Rudolf, R.
Anžel, I.
Powiązania:
https://bibliotekanauki.pl/articles/1808059.pdf
Data publikacji:
2009-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.-e
63.20.Kr
78.30.-j
Opis:
Far-infrared and magnetic properties of Ni doped PbTe ($Z_Ni$ = 1× $10^{19}$ at./$cm^{3}$) single crystal are investigated in a broad range of temperature and magnetic fields. Far-infrared reflection spectra were analyzed using a fitting procedure based on the modified plasmon-two phonon interaction model. Together with the strong plasmon-two longitudinal optical phonon coupling we obtained a local mode of Ni at about 180 $cm^{-1}$. This mode intensity depends on temperature. Magnetic measurements shows that PbTe alloys doped with Ni reveals weak ferromagnetic interaction between magnetic ions.
Źródło:
Acta Physica Polonica A; 2009, 115, 4; 805-807
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geometry of the $\text{}^4T_{2g}$ Excited State in $Cs_2SiF_6:Mn^{4+}$
Autorzy:
Reisz, A.
Avram, C.
Powiązania:
https://bibliotekanauki.pl/articles/1815472.pdf
Data publikacji:
2007-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ej
63.20.Kr
63.70.+h
Opis:
The aim of this paper is to calculate the equilibrium displacements of the $\text{}^4T_{2g}$ potential surface minimum from the ground state along the $a_{1g}$ and $e_g$ Jahn-Teller active modes for the octahedral $[MnF_6]^{2-}$ cluster obtained by doping $Mn^{4+}$ ions in $Cs_2SiF_6$ host crystal. The equilibrium displacements in normal and Cartesian coordinates were estimated from force constants of $[MnF_6]^{2-}$ cluster and Huang-Rhys factors associated with the Jahn-Teller stabilization energy. A net equatorial expansion and an axial stretching of the geometry of the $[MnF_6]_{2-}$ cluster in first $\text{}^4T_{2g}$ excited state, as combined effect of the $a_{1g}$ and $e_g$ displacements, were demonstrated.
Źródło:
Acta Physica Polonica A; 2007, 112, 5; 829-833
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman spectroscopy of shear modes in a few-layer MoS₂
Autorzy:
Gołasa, K.
Grzeszczyk, M.
Zinkiewicz, M.
Nogajewski, K.
Potemski, M.
Wysmołek, A.
Babiński, A.
Powiązania:
https://bibliotekanauki.pl/articles/1160654.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.-e
87.64.Je
63.20.Kr
Opis:
We study low frequency vibrational modes in atomically thin molybdenum disulfide (MoS₂) by means of the Raman scattering spectroscopy. A shear mode related to rigid interlayer vibrations is identified. Its energy evolution with the increasing number of layers is well described using a linear chain model with only nearest neighbor interactions. The resulting force constant (Kₓ = 2.7 × 10¹⁹ N/m³) corresponds well to the previously published data.
Źródło:
Acta Physica Polonica A; 2016, 129, 1a; A-132-A-134
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Transport and Microwave Noise in MBE- and MOCVD-Grown AlGaN/AlN/GaN
Autorzy:
Matulionis, A.
Liberis, J.
Eastman, L. F.
Schaff, W. J.
Shealy, J. R.
Chen, X.
Sun, Y. J.
Powiązania:
https://bibliotekanauki.pl/articles/2041771.pdf
Data publikacji:
2005-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
72.20.Ht
73.40.Kp
Opis:
Microwave noise temperature, current, and dissipated power were investigated at room temperature in undoped AlGaN/AlN/GaN channels grown by molecular beam epitaxy and metal-organic compound vapour decomposition techniques. Samples with essentially the same electron density (1×10$\text{}^{13}$ cm$\text{}^{-2}$) and low-field mobility (1150 cm$\text{}^{2}$/(V s)) demonstrated considerably different behaviour at high electric fields. The effective hot-phonon lifetime, 300 fs and 1000 fs, respectively, was estimated for molecular beam epitaxy and metal-organic compound vapour decomposition samples. The expected anti-correlation of hot-phonon lifetime and hot-electron drift velocity was confirmed experimentally.
Źródło:
Acta Physica Polonica A; 2005, 107, 2; 361-364
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Size Dependent Acoustical Properties of bcc Metal
Autorzy:
Yadav, R. R.
Pandey, D. K.
Powiązania:
https://bibliotekanauki.pl/articles/2043375.pdf
Data publikacji:
2005-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.Dc
62.65.+k
63.20.Kr
Opis:
The ultrasonic attenuation is evaluated at 300 K along [100], [110], and [111] directions for the characterization of bcc metal Ta. The size of the metal is considered in nanorange. Ultrasonic velocity, Grüneisen parameter and acoustic coupling constant that depend on second and third order elastic constants are calculated for determination of ultrasonic attenuation coefficient. Second and third order elastic constants of the bcc metal Ta at nanoscale at 300 K are also calculated starting with only two basic parameters. For the information about defects at nanoscale, the dislocation drag coefficients are calculated for the metal at different size along [100] orientation. The ultrasonic attenuation increases with the size of material as the size variation of the thermal conductivity and the thermal relaxation time. There is significant increase in the attenuation up to 150 nm.
Źródło:
Acta Physica Polonica A; 2005, 107, 6; 933-946
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Observation of Second-Generation Nonequilibrium Phonons in Highly Photoexcited CdS Microcrystals
Autorzy:
Kurilc̆ik, G.
Strumskis, M.
Jurs̆ėnas, S.
Z̆ukauskas, A.
Powiązania:
https://bibliotekanauki.pl/articles/1952036.pdf
Data publikacji:
1996-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
78.47.+p
78.55.Et
Opis:
Luminescence kinetics of nonthermalized electron-hole plasma in highly excited CdS microcrystals embedded in glass was studied at T=295 K using two pump pulses technique. The observed carrier kinetics shows additional increase in the effective temperature during the pump pulse as a result of the prepump pulse. The increase is shown to be produced by a fusion of long-lived second-generation nonequilibrium phonons generated by the prepump pulse. The experimental results are in good agreement with a model of hot electron-hole plasma energy relaxation with a build-up of two generations of nonequilibrium phonons.
Źródło:
Acta Physica Polonica A; 1996, 90, 5; 875-878
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Images of the Response Signal of a 2D Gas of Carriers to a Pulsed Beam of 3D Phonons
Autorzy:
Jasiukiewicz, Cz.
Lehmann, D.
Paszkiewicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1929698.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
63.20.Kr
66.70.+f
73.40.Lq
Opis:
The patterns for the time integrated drag current induced by a pulsed beam of bulk phonons in a 2D gas of charge carriers are calculated. A beam of Planckian phonons propagates in a GaAs crystal. We considered a 2D gas of electrons lying in a {001} plane and a 2D gas of holes lying in the {311} plane. Planckian phonons are radiated by an extended (Gaussian) source.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 661-664
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 23

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