Tunnelling splitting in jahn-teller centers of GaAs:Cu revealed by ultrasonic experiments
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2020-12-29 07:53
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AVERKIEV, Nikita, GUDKOV, V., BERSUKER, Isaac, BARYSHNIKOV, Kirill, ZHEVSTOVSKIKH, Irina, MAYAKIN, V., MONAKHOV, Andrey, SARYCHEV, M., SEDOV, V.. Tunnelling splitting in jahn-teller centers of GaAs:Cu revealed by ultrasonic experiments. In: Materials Science and Condensed Matter Physics, Ed. 6, 11-14 septembrie 2012, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2012, Editia 6, p. 129. ISBN 978-9975-66-290-1.
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Materials Science and Condensed Matter Physics
Editia 6, 2012
Conferința "Materials Science and Condensed Matter Physics"
6, Chișinău, Moldova, 11-14 septembrie 2012

Tunnelling splitting in jahn-teller centers of GaAs:Cu revealed by ultrasonic experiments


Pag. 129-129

Averkiev Nikita1, Gudkov V.2, Bersuker Isaac3, Baryshnikov Kirill1, Zhevstovskikh Irina24, Mayakin V.2, Monakhov Andrey1, Sarychev M.2, Sedov V.1
 
1 Ioffe Physical-Technical Institute, RAS,
2 Ural Federal University,
3 University of Texas at Austin,
4 Institute for Metal Physics, Ural Department of the Russian Academy of Sciences, Ekaterinburg
 
Disponibil în IBN: 19 martie 2020


Rezumat

Theoretical and experimental investigations of interaction between ultrasound and Jahn-Teller (JT) centers CuGa4As in GaAs crystal were performed. GaAs is a semiconducting crystal with the energy gap =1.51eV g E and sphalerite structure. Expressions for resonant and relaxation attenuation were derived including exchange interaction of two holes in the frames of the JT E ⊗e (Γ ⊗e) 8 problem [1]. Temperature dependences of attenuation α (T ) and phase velocity v(T ) for longitudinal and two shear ultrasonic waves propagating along the [110] crystallographic direction were obtained experimentally for the frequency of 53 MHz in the interval of 4.2÷100 K. Temperature dependences of the slow and fast shear modes in GaAs:Cu are shown in the figure by the curves 1 and 3, respectively. The Ccurve 2 relates to the slow shear mode in undoped GaAs. A peak of attenuation and anomalies in the velocity were observed at T ≈11K for the wave with displacements corresponding to the symmetry of the tetragonal E mode, namely, the slow shear wave the velocity of which is determined by the elastic modulus ( )/ 2 11 12 C C C s = − . The dependences α (T ) and v(T ) of this mode show that both relaxation and resonant interactions take place. Estimates of their contributions to the attenuation were obtained and the temperature dependence of the relaxation time was reconstructed. It justifies the tunnelling mechanism of relaxation at T <10 K . Based on the experimental data the magnitude of the tunnelling splitting [2] was evaluated as 0.7 GHz (in frequency unites) in good agreement with theoretical estimations. The authors appreciate financial support from Russian Foundation for Basic Research (grant No. 12-02-00476-a). [1] K. A. Baryshnikov, N. S. Averkiev, A. M. Monakhov, V. V. Gudkov. Physics of the Solid State 54 (2012) 468-477. [2] I. B. Bersuker. The Jahn-Teller Effect (Cambridge University Press, Cambridge, 2006) p.179-198.figure