Manifestation of the Jahn-Teller effect subject to quadraticT⊗e+t2problem in ultrasonic attenuation. Case study of CaF2:Cr crystal with isovalent and aliovalent substitution

Maksim N Sarychev; Wessam A L Hosseny; Irina V Zhevstovskikh; Vladimir A Ulanov; Gilman S Shakurov; Aleksandr V Egranov; Vladimir T Surikov; Nikita S Averkiev; Vladimir V Gudkov

doi:10.1088/1361-648X/ac533c

Manifestation of the Jahn-Teller effect subject to quadraticT⊗e+t2problem in ultrasonic attenuation. Case study of CaF₂:Cr crystal with isovalent and aliovalent substitution

J Phys Condens Matter. 2022 Apr 4;34(22). doi: 10.1088/1361-648X/ac533c.

Authors

Maksim N Sarychev¹, Wessam A L Hosseny^{1

2}, Irina V Zhevstovskikh^{1

3}, Vladimir A Ulanov^{4

5}, Gilman S Shakurov⁵, Aleksandr V Egranov^{6

7}, Vladimir T Surikov⁸, Nikita S Averkiev⁹, Vladimir V Gudkov¹

Affiliations

¹ Ural Federal University, Ekaterinburg 620002, Russia.
² Department of Physics, Faculty of Science, Benha University, Benha, 13511, Egypt.
³ M.N. Miheev Institute of Metal Physics, Ural Branch of Russian Academy of Sciences, Ekaterinburg 620108, Russia.
⁴ Kazan State Power Engineering University, Kazan, 420066, Russia.
⁵ E.K. Zavoisky Physical-Technical Institute, FRC Kazan Scientific Center of Russian Academy of Sciences, Kazan, 420029, Russia.
⁶ A.P. Vinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk, 664033, Russia.
⁷ Irkutsk State University, Irkutsk, 664003, Russia.
⁸ Institute of Solid State Chemistry, Ural Branch of Russian Academy of Sciences, Ekaterinburg 620990, Russia.
⁹ Ioffe Institute, St. Petersburg 194021, Russia.

PMID: 35139497
DOI: 10.1088/1361-648X/ac533c

Abstract

A new approach is introduced to obtain information about the adiabatic potential energy surface of the Jahn-Teller (JT) complexes subject to theT⊗e+t2problem in doped crystals. It employs simulation of the contribution of the JT sub-system to ultrasonic attenuation with account of three mechanisms of relaxation and subsequent comparison with the experimental data on temperature dependence of the attenuation obtained with the use of doped crystal and nominally pure one. The approach has been applied to the CaF₂crystal doped with chromium. The experiment has been carried out at the frequencies of (13-158) × 10⁶Hz at low temperatures (4-170 K). Peak for all the ultrasonic normal modes propagating along the [110] axis has been observed at about 8 K. It has been considered as the JT effect manifestation by the sub-system of Cr²⁺F8-complexes. Symmetry properties of the global minima and saddle points have been identified, the JT stabilization energies and coordinates of the extrema points in the five-dimensional space of symmetrized displacements have been evaluated. Besides, a broad shoulder has been found at 15-40 K and attributed to contribution of the Cr³⁺F8-sub-system.

Keywords: adiabatic potential energy surface; doped crystal; transition metal impurity; tunneling; ultrasonics.