Erratum: Ultrafast dephasing of coherent optical phonons in atomically controlled<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>GeTe</mml:mi><mml:mo>/</mml:mo><mml:msub><mml:mi>Sb</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>superlattices [Phys. Rev. B<b>79</b>, 174112 (2009)]

Hase, Muneaki; Miyamoto, Yoshinobu; Tominaga, Junji

doi:10.1103/physrevb.91.099906

Cited by 11 publications

(18 citation statements)

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“…The phonon frequencies of these three modes are basically consistent with previously reported values20. The assignment of phonon modes in iPCM remains controversial, the 2.1 THz and 5.1 THz modes can be assigned to two different A 1 modes in the Sb 2 Te 3 sub-layers while the 3.4 THz mode may be a E g mode in the Sb 2 Te 3 sub-layers or the A 1 mode in the GeTe sub-layers2021222324. As seen in Fig.…”

Section: Resultssupporting

confidence: 90%

Anisotropic lattice response induced by a linearly-polarized femtosecond optical pulse excitation in interfacial phase change memory material

Makino

Saito

Fons

et al. 2016

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Optical excitation of matter with linearly-polarized femtosecond pulses creates a transient non-equilibrium lattice displacement along a certain direction. Here, the pump and probe pulse polarization dependence of the photo-induced ultrafast lattice dynamics in (GeTe)2/(Sb2Te3)4 interfacial phase change memory material is investigated under obliquely incident conditions. Drastic pump polarization dependence of the coherent phonon amplitude is observed when the probe polarization angle is parallel to the c–axis of the sample, while the pump polarization dependence is negligible when the probe polarization angle is perpendicular to the c–axis. The enhancement of phonon oscillation amplitude due to pump polarization rotation for a specific probe polarization angle is only found in the early time stage (≤2 ps). These results indicate that the origin of the pump and probe polarization dependence is dominantly attributable to the anisotropically-formed photo-excited carriers which cause the directional lattice dynamics.

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Section: Resultssupporting

confidence: 90%

Anisotropic lattice response induced by a linearly-polarized femtosecond optical pulse excitation in interfacial phase change memory material

Makino

Saito

Fons

et al. 2016

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“…Knowledge and understanding of the phonon spectrum can provide a fingerprint of the crystallographic structure while large amplitude phonons may appear as a precursor to the phase transition itself. Although several studies of coherent optical phonon (COP) dynamics have been performed upon both amorphous and polycrystalline Ge 2 Sb 2 Te 5 56789, no such study has been conducted on a Ge 2 Sb 2 Te 5 single crystal. Therefore the growth of epitaxial Ge 2 Sb 2 Te 5 films upon GaSb(001) substrates10 by molecular beam epitaxy provides an opportunity to explore the character of the phonon spectrum of Ge 2 Sb 2 Te 5 .…”

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confidence: 99%

Observation of T2-like coherent optical phonons in epitaxial Ge2Sb2Te5/GaSb(001) films

Shalini

Liu

Al-Jarah

et al. 2013

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The phonon spectrum of Ge2Sb2Te5 is a signature of its crystallographic structure and underlies the phase transition process used in memory applications. Epitaxial materials allow coherent optical phonons to be studied in femtosecond anisotropic reflectance measurements. A dominant phonon mode with frequency of 3.4 THz has been observed in epitaxial Ge2Sb2Te5 grown on GaSb(001). The dependence of signal strength upon pump and probe polarization is described by a theory of transient stimulated Raman scattering that accounts for the symmetry of the crystallographic structure through use of the Raman tensor. The 3.4 THz mode has the character of the 3 dimensional T2 mode expected for the Oh point group, confirming that the underlying crystallographic structure is cubic. New modes are observed in both Ge2Sb2Te5 and GaSb after application of large pump fluences, and are interpreted as 1 and 2 dimensional modes associated with segregation of Sb.

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“…Recently, extensive theoretical studies such as molecular dynamics simulations and experimental studies such as extended X-ray absorption fine structure and Raman scattering measurements have been made on GST in order to investigate its structure. These studies suggest that crystalline GST has a distorted rock-salt structure with a high density of vacancies, from which the amorphous phase is reached by an umbrella flip of certain Ge atoms from sites of octahedral to tetrahedral coordination [3]. The amorphous phase contains Ge-Ge and Ge-Sb bonds referred as ''wrong bonds'' which are not expected to be present in the crystalline structure.…”

Section: Introductionmentioning

confidence: 95%

“…Coherent optical spectroscopy (CPS) is an attractive tool with which to study ultrafast lattice dynamics and structural phase transitions on ps and fs time scales. The pump pulse excites coherent lattice vibrations through electronic transitions when the duration of the pump pulse is shorter than the period of vibration, and so phonons with THz frequencies may be readily excited [2,3].…”

Section: Introductionmentioning

confidence: 99%

Excitation and detection of coherent optical phonon modes in epitaxial cubic Ge₂Sb₂Te₅thin films of different crystallographic orientation

et al. 2014

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Optical pump-probe studies of cubic crystalline Ge 2 Sb 2 Te 5 /GaSb(001) have previously shown that the amplitude of a coherent optical phonon (COP) with frequency of 3.4 THz observed in the anisotropic reflectance ( ) signal exhibits a four-fold dependence upon the polarization of the probe beam. The appearance of the mode in the signal but not the reflectance ( ) signal, and the dependence upon probe polarization, both suggest a three-dimensional mode character. Confirmation that this mode indeed has three-dimensional character, similar to the Raman inactive mode in the pristine rock salt structure, is highly important in understanding the structure of the crystalline phase of Ge 2 Sb 2 Te 5 that has important applications within data storage technology. A phonon of the same frequency has been observed in an epitaxial Ge 2 Sb 2 Te 5 /InAs(111) structure, suggesting that this phonon is indeed characteristic of epitaxial cubic GST. A theory, which considers the symmetry of the Raman tensor for a particular phonon mode, is used to predict the dependence of R and AR signal amplitude upon pump and probe polarization for the mode of a (111) facet of the putative rock-salt structure.

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Erratum: Ultrafast dephasing of coherent optical phonons in atomically controlledGeTe/Sb2Te3superlattices [Phys. Rev. B79, 174112 (2009)]

Cited by 11 publications

References 2 publications

Anisotropic lattice response induced by a linearly-polarized femtosecond optical pulse excitation in interfacial phase change memory material

Anisotropic lattice response induced by a linearly-polarized femtosecond optical pulse excitation in interfacial phase change memory material

Observation of T2-like coherent optical phonons in epitaxial Ge2Sb2Te5/GaSb(001) films

Excitation and detection of coherent optical phonon modes in epitaxial cubic Ge₂Sb₂Te₅thin films of different crystallographic orientation

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Erratum: Ultrafast dephasing of coherent optical phonons in atomically controlledGeTe/Sb2Te3superlattices [Phys. Rev. B79, 174112 (2009)]

Cited by 11 publications

References 2 publications

Anisotropic lattice response induced by a linearly-polarized femtosecond optical pulse excitation in interfacial phase change memory material

Anisotropic lattice response induced by a linearly-polarized femtosecond optical pulse excitation in interfacial phase change memory material

Observation of T2-like coherent optical phonons in epitaxial Ge2Sb2Te5/GaSb(001) films

Excitation and detection of coherent optical phonon modes in epitaxial cubic Ge2Sb2Te5thin films of different crystallographic orientation

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Excitation and detection of coherent optical phonon modes in epitaxial cubic Ge₂Sb₂Te₅thin films of different crystallographic orientation