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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
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Effect of ferromagnetic ordering on phonons in KCo2Se2
Urszula D Wdowik1, Grzegorz Jagło, Przemysław Piekarz
1Institute of Technology, Pedagogical University, ul. Podchorazych 2, 30-084 Cracow, Poland.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|September 30, 2015
Summary
Density functional theory reveals strong spin-phonon coupling in KCo2Se2. Ferromagnetic order significantly influences phonon dynamics, affecting Raman and infrared spectra, and distinguishing it from paramagnetic analogs.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid State Chemistry
Background:
- Ternary layered cobalt diselenides (KCo2Se2) exhibit unique structural and magnetic properties.
- Understanding phonon dynamics is crucial for elucidating their electronic and magnetic behavior.
- Comparison with paramagnetic analogs (Ni-based) highlights the role of magnetism.
Purpose of the Study:
- Investigate phonon dynamics in KCo2Se2 using density functional theory.
- Analyze the contribution of K, Co, and Se atoms to phonon densities of states.
- Clarify the influence of ferromagnetic order and spin-phonon coupling on material properties.
Main Methods:
- Density Functional Theory (DFT) calculations.
- Analysis of partial phonon densities of states (PDOS).
- Calculation and interpretation of Raman and infrared spectra.
Main Results:
- Phonons from Co and Se ions span 0-260 cm⁻¹, while K-sublattice phonons are confined to 80-150 cm⁻¹.
- Ferromagnetic order in the Co-sublattice strongly affects phonon densities of states and spectra.
- Spin-phonon coupling leads to softening of high-frequency modes and disappearance of a low-frequency Raman mode.
Conclusions:
- Strong spin-phonon coupling is evident in KCo2Se2.
- Magnetic interactions significantly influence phonon behavior, explaining differences with paramagnetic Ni-based compounds.
- The study provides insights into the dynamical properties of ferromagnetic layered dichalcogenides.
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