Spatial Distortion of Vibration Modes via Magnetic Correlation of Impurities

Long wavelength vibrational modes in the ferromagnetic semiconductor Ga_{0.91}Mn_{0.09}As are investigated using time resolved x-ray diffraction. At room temperature, we measure oscillations in the x-ray diffraction intensity corresponding to coherent vibrational modes with well-defined wavelengths....

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Bibliographic Details
Published in:Physical review letters 2018-03, Vol.120 (10), p.105501-105501, Article 105501
Main Authors: Krasniqi, F S, Zhong, Y, Epp, S W, Foucar, L, Trigo, M, Chen, J, Reis, D A, Wang, H L, Zhao, J H, Lemke, H T, Zhu, D, Chollet, M, Fritz, D M, Hartmann, R, Englert, L, Strüder, L, Schlichting, I, Ullrich, J
Format: Article
Language:English
Subjects:
Electrical resistivity
Ferromagnetism
Impurities
Lattice vibration
MATERIALS SCIENCE
Plane waves
Superposition (mathematics)
Thermal management
Vibration analysis
Vibration mode
Wavelengths
X-ray diffraction
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Summary:Long wavelength vibrational modes in the ferromagnetic semiconductor Ga_{0.91}Mn_{0.09}As are investigated using time resolved x-ray diffraction. At room temperature, we measure oscillations in the x-ray diffraction intensity corresponding to coherent vibrational modes with well-defined wavelengths. When the correlation of magnetic impurities sets in, we observe the transition of the lattice into a disordered state that does not support coherent modes at large wavelengths. Our measurements point toward a magnetically induced broadening of long wavelength vibrational modes in momentum space and their quasilocalization in the real space. More specifically, long wavelength vibrational modes cannot be assigned to a single wavelength but rather should be represented as a superposition of plane waves with different wavelengths. Our findings have strong implications for the phonon-related processes, especially carrier-phonon and phonon-phonon scattering, which govern the electrical conductivity and thermal management of semiconductor-based devices.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.120.105501