Designing sustainable permanent magnets tailored by light elements

Abstract

Designing sustainable permanent magnets tailored by light elements High performance permanent magnets have a vast spectrum of applications in efficient energy harvesting and energy conversion. Thus, there is a strong impetus to design sustainable permanent magnets which do not rely on critical elements and can fill the gap between the current high- (e.g., Sm-Co and Nd-Fe-B) and low-performance (e.g., AlNiCo and ferrite) systems [1]. In this work, focusing on the intrinsic magnetic properties, we will demonstrate how to design permanent magnets tailored by light elements such as H, B, C, and N, based on high-throughput density functional theory calculations. After clarifying the simulation challenges and establishing the practical workflow [2], we will elucidate two strategies to integrate the light elements (i) as interstitials [3-6] and (ii) by forming novel phases [7]. Detailed analysis reveals that the light elements have a strong influence on the crystal fields by modifying the local chemical bonds and hence are an efficient tool to tune the magneto-crystalline anisotropy. Lastly, we summarise the open questions to bridge to experiments and give an outlook on how such concepts can be transferred to magnetic materials for other applications such as magnetocaloric cooling and spintronics. [1] K.P. Skokov and O. Gutfleisch, Scripta Materialia 154, 289 (2018). [2] H. Zhang, Electronic Structure (accepted) doi:10.1088/2516-1075/abbb25 [3] H. Zhang, I. Dirba, T. Helbig, L. Alff, and O. Gutfleisch, APL Materials 4, 116104 (2016). [4] D. Gölden, H. Zhang, I. Radulov, I. Dirba, P. Komissinskiy, E. Hildebrandt, and L. Alff, Phys. Rev. B 97, 014411 (2018). [5] Q. Gao, I. Opahle, O. Gutfleisch, and H. Zhang, Acta Materialia 186, 355 (2020). [6] X. Ye, H.K. Singh, H. Zhang, H. Gewein, K.P. Skokov, C.M. Reda, T. Schrefl, O. Gutfleisch, R. Witte, A. Molinari, H. Hahn, and R. Kruk, Nature Communications 11, 4849 (2020). [7] C. Shen, Q. Gao, N.M. Fortunato, H.K. Singh, I. Opahle, O. Gutfleisch, and H. Zhang, J. Mat. Chem. A (online) doi:10.1039/D0TA11026D