scholarly journals Anomalous transverse acoustic phonon broadening in the relaxor ferroelectricPb(Mg1/3Nb2/3)0.8Ti0.2O3

2002 ◽  
Vol 65 (14) ◽  
Author(s):  
T. Y. Koo ◽  
P. M. Gehring ◽  
G. Shirane ◽  
V. Kiryukhin ◽  
S.-G. Lee ◽  
...  
Keyword(s):  
Acoustic Phonon ◽  
Transverse Acoustic

scholarly journals Ultralow thermal conductivity from transverse acoustic phonon suppression in distorted crystalline α-MgAgSb

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiyang Li ◽  
Peng-Fei Liu ◽  
Enyue Zhao ◽  
Zhigang Zhang ◽  
Tatiana Guidi ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Acoustic Phonon ◽  
Transverse Acoustic

Disorder-induced Raman scattering of In1−xGaxP in the transverse acoustic phonon region

1981 ◽  
Vol 37 (12) ◽  
pp. 963-966 ◽  
Author(s):  
B.H. Bayramov ◽  
V.V. Toporov ◽  
Sh.B. Ubaydullaev ◽  
L. Hildisch ◽  
E. Jahne
Keyword(s):  
Raman Scattering ◽  
Acoustic Phonon ◽  
Transverse Acoustic

Magnons and Phonons in Cobalt Ferrite

1974 ◽  
Vol 52 (5) ◽  
pp. 396-398 ◽  
Author(s):  
H. C. Teh ◽  
M. F. Collins ◽  
H. A. Mook
Keyword(s):  
Acoustic Phonon ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Zone Boundary ◽  
Phonon Branch ◽  
Longitudinal Acoustic ◽  
Transverse Acoustic ◽  
Low Energies ◽  
Longitudinal Acoustic Phonon ◽  
Infrared Data

Magnons and phonons have been observed in a single crystal of cobalt ferrite, CoFe2O1 at room temperature. Dispersion relations are plotted for the [001] and the [111] directions. The longitudinal acoustic phonon branch has been measured out to the zone boundary in both directions, while the transverse acoustic branch has been completely determined only in the [001] direction. The acoustic magnon branches are well defined at low energies, but they rapidly lose intensity and disappear at around 9 THz. We have not determined uniquely why this happens, but some possibilities are given. Optic branches have been observed at around 11.3 and 14.0 THz. Infrared data indicate that the first branch is probably of phonon character and the second of magnon character.

Pressure dependence of transverse acoustic phonon energy in ferropericlase across the spin transition

2017 ◽  
Vol 29 (24) ◽  
pp. 245401 ◽  
Author(s):  
Hiroshi Fukui ◽  
Alfred Q R Baron ◽  
Daisuke Ishikawa ◽  
Hiroshi Uchiyama ◽  
Yasuo Ohishi ◽  
...  
Keyword(s):  
Pressure Dependence ◽  
Acoustic Phonon ◽  
Spin Transition ◽  
Phonon Energy ◽  
Transverse Acoustic

The Phonon Thermal Conductivity of a Single-Layer Graphene From Complete Phonon Dispersion Relations

2010 ◽  
Author(s):  
Yunfeng Gu ◽  
Zhonghua Ni ◽  
Minhua Chen ◽  
Kedong Bi ◽  
Yunfei Chen
Keyword(s):  
Thermal Conductivity ◽  
Acoustic Phonon ◽  
Phonon Scattering ◽  
Phonon Dispersion ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Optical Phonons ◽  
Relaxation Rates ◽  
Phonon Thermal Conductivity ◽  
Transverse Acoustic

In this paper, the phonon scattering mechanisms of a single layer graphene are investigated based on the complete phonon dispersion relations. According to the selection rules that a phonon scattering process should obey the energy and momentum conservation conditions, the relaxation rates of combing and splitting Umklapp processes can be calculated by integrating the intersection lines between different phonon mode surfaces in the phonon dispersion relation space. The dependence of the relaxation rates on the wave vector directions is presented with a three dimensional surfaces over the first Brillion zone. It is found that the reason for the optical phonons contributing a little to heat transfer is attributed to the strong Umklapp processes but not to their low group velocities. The combing Umklapp scattering processes involved by the optical phonons mainly decrease the acoustic phonon thermal conductivity, while the splitting Umklapp scattering processes of the optical phonons mainly restrict heat conduction by the optical phonons themselves. Neglecting the splitting processes, the optical phonons can contribute more energy than that carried by the acoustic phonons. Based on the calculated phonon relaxation time, the thermal conductivities contributed from different mode phonons can be evaluated. At low temperatures, both longitudinal and in-plane transverse acoustic phonon thermal conductivities have T2 temperature dependence, and the out-of-plane transverse acoustic phonon thermal conductivity is proportion to T3/2. At room temperature, the calculated thermal conductivity is on the order of a few thousands W/m.K depending on the sample size and the edge roughness, which is in agreement with the recently measured data.

scholarly journals Investigating anomalous thermal expansion of copper halides by inelastic neutron scattering and ab initio phonon calculations

2017 ◽  
Vol 19 (19) ◽  
pp. 12107-12116 ◽  
Author(s):  
Abhijith M. Gopakumar ◽  
M. K. Gupta ◽  
R. Mittal ◽  
S. Rols ◽  
S. L. Chaplot
Keyword(s):  
Thermal Expansion ◽  
Neutron Scattering ◽  
Ab Initio ◽  
Acoustic Phonon ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Volume Dependence ◽  
Transverse Acoustic ◽  
Anomalous Thermal Expansion ◽  
Copper Halides

The volume dependence of the frequency of the soft transverse acoustic phonon explains the anomalous thermal expansion in CuX.

scholarly journals Two-colour Three-pulse Spectrally Resolved Nonlinear Spectroscopy for Studies of Dynamics in Semiconductor Si Quantum Dots

2020 ◽  
Vol 30 (1) ◽  
pp. 79
Author(s):  
Vuong Van Cuong ◽  
Dinh Ba Khuong ◽  
Dao Van Lap
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Optical Phonon ◽  
Acoustic Phonon ◽  
Nonlinear Spectroscopy ◽  
Transverse Optical ◽  
Transverse Acoustic ◽  
Spectrally Resolved ◽  
Si Quantum Dots

We demonstrate that a two-colour three-pulsenonlinear spectroscopy can be used to study the dynamics of excited carriers inSi quantum dot structures embedded in SiN. Decays of the transverse optical phonon population and the transverse acoustic phonon population are measured and discussed. A simple theoretical modelis also used to support interpretation of our experimental observations.

scholarly journals Resonance damping of the terahertz-frequency transverse acoustic phonon in the relaxor ferroelectricKTa1−xNbxO3

2016 ◽  
Vol 94 (21) ◽  
Author(s):  
J. Toulouse ◽  
E. Iolin ◽  
B. Hennion ◽  
D. Petitgrand ◽  
R. Erwin
Keyword(s):  
Acoustic Phonon ◽  
Terahertz Frequency ◽  
Transverse Acoustic ◽  
Resonance Damping

The Phonon Thermal Conductivity of Single-Layer Graphene From Complete Phonon Dispersion Relations

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Yunfeng Gu ◽  
Zhonghua Ni ◽  
Minhua Chen ◽  
Kedong Bi ◽  
Yunfei Chen
Keyword(s):  
Thermal Conductivity ◽  
Acoustic Phonon ◽  
Phonon Scattering ◽  
Phonon Dispersion ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Optical Phonons ◽  
Relaxation Rates ◽  
Phonon Thermal Conductivity ◽  
Transverse Acoustic

In this paper, the phonon scattering mechanisms of single-layer graphene are investigated based on the complete phonon dispersion relations. According to the selection rules that a phonon scattering process should obey the energy and momentum conservation conditions, the relaxation rates of combining and splitting umklapp processes can be calculated by integrating the intersection lines between different phonon mode surfaces in the phonon dispersion relation space. The dependence of the relaxation rates on the wave vector directions is presented with a three-dimensional surface over the first Brillouin zone. It is found that the reason for the optical phonons contributing little to heat transfer is attributed to the strong umklapp processes but not to their low phonon group velocities. The combining umklapp scattering processes involving the optical phonons mainly decrease the acoustic phonon thermal conductivity, while the splitting umklapp scattering processes of the optical phonons mainly restrict heat conduction by the optical phonons themselves. Neglecting the splitting processes, the optical phonons can contribute more energy than that carried by the acoustic phonons. Based on the calculated phonon relaxation time, the thermal conductivities contributed from different mode phonons can be evaluated. At low temperatures, both longitudinal and in-plane transverse acoustic phonon thermal conductivities have T2 temperature dependence, and the out-of-plane transverse acoustic phonon thermal conductivity is proportion to T3/2. The calculated thermal conductivity is on the order of a few thousands W/(m K) at room temperature, depending on the sample size and the edge roughness, and is in agreement well with the recently measured data in the temperature range from about 350 K to 500 K.

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