Presentation Information
[P1-70]Towards the high-throughput microstructural characterisation of compositionally graded NdFeB-based films
*Lukas Fink1, William Rigaut1, Pierre Le-Berre1, Heisam Moustafa2, Qais Ali2, Leoni Breth2, Thomas Schrefl2, Harald Oezelt2, Thibaut Devillers1, Nora M. Dempsey1 (1. 1Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble (France), 2. Department for Integrated Sensor Systems, University for Continuing Education Krems, 2700 Wr. Neustadt (Austria))
Keywords:
High-throughput characterisation,Thin film,Microstructure
In the ongoing efforts to reduce CO2 emissions, there has been a drastic increase in the utilisation of environmentally sustainable technologies for power generation and transportation. Nevertheless, the prevailing reliance on magnetic materials poses a considerable challenge since these materials are composed of rare earth and cobalt, among other critical elements. Therefore, the objective is to identify novel magnetic materials that can match the properties of existing materials while demonstrating superior environmental and economic viability. Achieving this goal requires screening a vast number of materials, but conventional methods limit exploration to compositions near known materials. A promising approach is combinatorial studies based on the preparation of compositionally graded films [1]. These enable efficient screening and optimisation of functional materials, through the use of high throughput characterization methods. In the case of hard magnetic FePt [2] and NdFeB-based [3] films, high-throughput characterization made it possible to systematically analyse the extrinsic magnetic properties, the chemical composition and the crystal structure, enabling the correlation of trends and identification of causal relationships. However, variations in microstructure have not been considered in these investigations. This is of particular relevance, given the established influence of microstructure on the extrinsic magnetic properties of hard magnetic materials.
In this study, we establish a high-throughput methodology for microstructural characterisation of NdFeB-based films, using argon Ion Beam Etching (IBE) followed by plan-view Scanning Electron Microscopy (SEM) imaging. The etching step is used to fully remove the protective 10 nm Ta capping layer, and to partially remove material from the upper surface of the NdFeB-based film. The prominence of the revealed microstructural features depends of the duration of etching (Fig. 1). After 10 minutes of etching, the grain structure of the main 2:14:1 phase is discernible through the presence of voids, known to form in such films [4]. After 25 minutes of etching, individual grains of the main 2:14:1 phase can be clearly distinguished, thanks to preferential etching of the rare earth rich secondary phases. The latter type of images are well suited to grain size distribution analysis. By automating wafer-level SEM imaging and image analysis across compositionally graded films, we can map the lateral distribution of different microstructural features. This can then contribute to establishing correlations between structural and magnetic properties, through machine learning analysis and micromagnetic modelling [5]. This approach enhances the efficiency of combinatorial materials screening, providing deeper insights into structure-property relationships critical for next-generation magnetic materials.
[1] ML Green et al., J. Appl. Phys. 113 (2013) 231101
[2] Y. Hong et al., J. Mater. Res. Technol. 18 (2022) 1245
[3] A. Kovacs et al., Front. Mater 9 (2023) 1094055
[4] N.M. Dempsey et al., , Acta. Mat. 61 (2013) 4920
[5] H. Moustafa et al., AIP Advances 14 (2024) 025001
Acknowledgements: This work is being carried out within the framework of the EU funded MaMMoS project (Grant number 101135546, HORIZON-CL4-2023-DIGITAL-EMERGING-01), the ANR-FWF funded DATAMAG project (ANR-22-CE91-0008 / FWF I 6159-N) and the ANR/DIADEM MIAM project (ANR-23-PEXD-0013).
In this study, we establish a high-throughput methodology for microstructural characterisation of NdFeB-based films, using argon Ion Beam Etching (IBE) followed by plan-view Scanning Electron Microscopy (SEM) imaging. The etching step is used to fully remove the protective 10 nm Ta capping layer, and to partially remove material from the upper surface of the NdFeB-based film. The prominence of the revealed microstructural features depends of the duration of etching (Fig. 1). After 10 minutes of etching, the grain structure of the main 2:14:1 phase is discernible through the presence of voids, known to form in such films [4]. After 25 minutes of etching, individual grains of the main 2:14:1 phase can be clearly distinguished, thanks to preferential etching of the rare earth rich secondary phases. The latter type of images are well suited to grain size distribution analysis. By automating wafer-level SEM imaging and image analysis across compositionally graded films, we can map the lateral distribution of different microstructural features. This can then contribute to establishing correlations between structural and magnetic properties, through machine learning analysis and micromagnetic modelling [5]. This approach enhances the efficiency of combinatorial materials screening, providing deeper insights into structure-property relationships critical for next-generation magnetic materials.
[1] ML Green et al., J. Appl. Phys. 113 (2013) 231101
[2] Y. Hong et al., J. Mater. Res. Technol. 18 (2022) 1245
[3] A. Kovacs et al., Front. Mater 9 (2023) 1094055
[4] N.M. Dempsey et al., , Acta. Mat. 61 (2013) 4920
[5] H. Moustafa et al., AIP Advances 14 (2024) 025001
Acknowledgements: This work is being carried out within the framework of the EU funded MaMMoS project (Grant number 101135546, HORIZON-CL4-2023-DIGITAL-EMERGING-01), the ANR-FWF funded DATAMAG project (ANR-22-CE91-0008 / FWF I 6159-N) and the ANR/DIADEM MIAM project (ANR-23-PEXD-0013).
