Ultrasonic evaluation of the Jahn-Teller effect parameters. Application to ZnSe:Cr2+
V V Gudkov1, I B Bersuker, I V Zhevstovskikh
1Ural Federal University, Ekaterinburg, Russia. gudkov@imp.uran.ru
Summary
Ultrasonic experiments reveal Jahn-Teller (JT) effect parameters in crystals. This method quantifies vibronic coupling constants and adiabatic potential energy surfaces for impurity centers like Cr(2+) in ZnSe.
Area of Science:
- Solid State Physics
- Materials Science
- Crystallography
Background:
- The Jahn-Teller (JT) effect significantly influences the properties of impurity centers in crystals.
- Understanding JT effect parameters is crucial for predicting and controlling material behavior.
- Existing methods often require assumptions about relaxation mechanisms, limiting their applicability.
Purpose of the Study:
- To develop and validate a novel method for evaluating JT effect parameters using ultrasonic experiments.
- To determine the vibronic coupling constants and adiabatic potential energy surface (APES) for specific impurity systems.
- To investigate the influence of different vibronic modes on the elastic properties of crystals.
Main Methods:
- Utilized temperature-dependent ultrasonic attenuation and phase velocity measurements.
- Applied the method to the ZnSe:Cr(2+) impurity system, focusing on the [Formula: see text] JT problem.
- Analyzed ultrasound propagation anomalies to deduce JT distortions and coupling parameters without assuming relaxation mechanisms.
Main Results:
- Determined the modulus of the linear vibronic coupling constant |F(E)| for Cr(2+) in ZnSe to be approximately 5.5 × 10(-5) dyn via independent attenuation and phase velocity measurements.
- Identified tetragonal E-type distortions as the primary JT distortions for Cr(2+) in ZnSe.
- Estimated the primary force constant K(E) and stabilization energies for orthorhombic (E(JT)(O)≈81–450 cm(-1)) and trigonal (E(JT)(T)≈48–417 cm(-1)) saddle points of the APES.
Conclusions:
- The developed ultrasonic method effectively evaluates JT effect parameters without prior assumptions on relaxation.
- The study reveals detailed characteristics of the APES for the Cr(2+) ion in ZnSe, confirming the [Formula: see text] JT problem.
- The findings provide valuable insights into the vibronic interactions governing the properties of impurity centers in crystalline materials.
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