Electronic structure and lattice dynamics of Ba2CuTeO6 single crystals
| Autor: | Sunil K. Karna, Yun Chen Chung, F. C. Chou, Hsiang Lin Liu |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Phase transition
Materials science Absorption spectroscopy Phonon Band gap General Chemical Engineering 02 engineering and technology General Chemistry Electronic structure 021001 nanoscience & nanotechnology 01 natural sciences Molecular physics symbols.namesake Absorption band 0103 physical sciences symbols Antiferromagnetism 010306 general physics 0210 nano-technology Raman scattering |
| Zdroj: | RSC Advances. 10:20067-20072 |
| ISSN: | 2046-2069 |
| Popis: | The electronic structure and lattice dynamics of Ba2CuTeO6 single crystals were investigated through spectroscopic ellipsometry and Raman scattering measurements. The room-temperature optical absorption spectrum of Ba2CuTeO6 presented a direct optical band gap at approximately 1.04 eV and exhibited four bands at approximately 1.45, 3.43, 4.65, and 5.79 eV. The optical absorption band at 1.45 eV was attributed to on-site Cu2+ d–d transition. The other bands were attributed to charge-transfer transitions between the O 2p and Cu 3d or Te 5p states. The room-temperature Raman scattering spectrum of Ba2CuTeO6 exhibited 16 phonon modes at approximately 85, 97, 104, 119, 160, 194, 380, 396, 404, 409, 492, 568, 574, 606, 679, and 751 cm−1. When the temperature decreased to less than 287 K, which is the temperature at which structural phase transition occurs from the monoclinic phase to the triclinic phase, additional phonon modes appeared at approximately 124, 128, 152, and 601 cm−1. On further cooling to lower than 75 and 15 K, which are the temperatures at which short- and long-range antiferromagnetic phase transitions occur, respectively, the phonon modes at approximately 97, 104, 124, 128, 152, 160, 194, 380, 396, 409, 568, 574, 606, and 679 cm−1 exhibited softening, which indicates a coupling between the magnetic and lattice degrees of freedom. The stretching vibration of CuO6 octahedra located at 679 cm−1 had the largest spin–phonon coupling constant (1.67 mRy A−2). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|