Ce 4f configuration under different crystal environments calculated by DFT+DMFT approach. The RE (rare earth)-TM (transition metal) based intermetallic compounds are a series of promising candidates for permanent magnets. There exists a variety of RE-TM intermetallics with different crystalline structures. Through this project we would like to perform a thorough theoretical investigation on the relationship between the crystal structure and the intrinsic magnetic properties, in order to provide useful guidance on material design for a well-performed permanent magnet. The necessity of using high-performance supercomputing service is due to the high computational power and parallelization required by the main computational method used. The number of cores used in the calculation decides the size of sampling in a statistical method. In other words, more cores always give better statistics and thus more accurate results.
Project Details
Project term
May 1, 2023–April 30, 2024
Affiliations
RWTH Aachen University
Institute
Institute of Materials Science
Principal Investigator
Methods
The calculations were carried out mainly using the DFT + DMFT approach in order to treat appropriately the strongly correlated feature of RE 4f states. In addition, in one collaboration work with experimentalist, the DFT + U method was adopted to calculate the magnetic exchange coupling parameters. Subsequently, using the calculated magnetic exchange parameters, the atomistic spin dynamics simulation was performed using UppASD to unveil the evoluetion of magnetic configuration with temperature.
Results
We have performed a series of DFT + DMFT calculations to investigate the magnetic properties of Ce-based RE-TM intermetallics, including CeCo5, Cu-doped CeCo5, CeCo4B, CeCo3B2, CeCo12, Ce2Co17, and Sm-based intermetallics, e.g., SmCo5, Cu-doped SmCo5, Sm2Fe17, Sm2Fe17N3, as well as TbCo amorphous systems. The electronic structures and magnetic anisotropies of RE-TM based systems are highly dependent on its local chemical environments.
Discussion
Through a series of calculations, especially the magnetic anisotropy energies of the RE elements that are located at various local chemical environments, we realized that tuning local chemical environments would be an effective way to enhance the magnetic anisotropy. For example, in TbCo amorphous systems, hydrogen charging can be used as a way to altering and controlling the easy magnetization axis. Additionally, the results can be reused in the future to map the correlations between local crystal structure and magnetic anisotropy facilitated by machine learning. In other words, given the chemical enviroment of a RE element, one can predict the magnetic anisotropy using the trained surrogate model. Furthermore, it is also possible to achieve the inverse design of optimal crystalline environements with high magnetic anisotropy.
Additional Project Information
DFG classification: 406 Materials Science
Software: VASP, UppASD, Wien2k, eDMFT, Quanty
Cluster: CLAIX
Publications
Jianing Liu, Ruiwen Xie, Alex Aubert, Lukas Schäfer, Hongbin Zhang, Oliver Gutfleisch, Konstantin Skokov, Magnetic properties of Nd6Fe13Cu single crystals. 2023. Applied Physics Letters, 122.
Georgia Gkouzia, Damian Günzing, Ruiwen Xie, et al. Element-specific study of magnetic anisotropy and hardening in SmCo5−xCux thin films. 2023. Inorganic Chemistry, 62.