Functional materials ѥBBeff acc. layer \SB p-Si Ni Si N Fermi level cond. band val. band MSi vac. level MNi d p-Si Ni Si N Fermi level MSi MNi d acc. layer jT a) b) a) b) c) d) e) S. Laterza1,2, A. Caretta2, R. Bhardwaj2, P. Moras3, N. Zema4, R. Flammini4, M. Malvestuto2,5 1 Department of Physics, University of Trieste, Trieste, Italy. 2 Elettra-Sincrotrone Trieste S.C.p.A., Trieste, Italy. 3 CNR-ISM, Consiglio Nazionale Delle Ricerche, Trieste, Italy. 4 CNR-ISM, Consiglio Nazionale Delle Ricerche, Rome, Italy. 5 CNR-IOM, Consiglio Nazionale Delle Ricerche, Trieste, Italy. e-mail: simone.laterza@elettra.eu Acknowledgments We acknowledge Elettra Sincrotrone Trieste for providing access to its synchrotron radiation facilities and for financial support. The research leading to this result has been supported by the project Laserlab-Europe under Grant Agreement 871124 from the EU Framework Programme for Research and Innovation HORIZON 2020. Original paper S. Laterza et al., Scientific Reports 14, 1329 (2024); DOI: 10.1038/s41598-023-50795-w. Fig. 1 Figure 1. Origin of magnetism and XMCD signal from Ni/Si heterostructures. The metal/p-Si interface electronic band structure outlines the two possible scenarios for the build-up of magnetism in the charge-accumulation layer of Si (MSi, red highlighted region in a and b); either a spin-polarized tunneling current jT from Ni propagates into the accumulation zone in Si (a), or the magnetic field MNi produced by the Ni layer alters the energy distribution in Si and causes the band structure to be spin-splitted - the splitting amounting to µBBeff (b). In either case, an asymmetry of spin-up/down population arises at the Ni/Si interface. The XMCD signal in reflectivity has been collected on two different samples with low and high-doped substrates; at the Ni M2,3 edge element-specific magnetization reveals a similar signal for the two samples (c), whereas the induced spin polarization at the Si L2,3 edge for low-doped Si shows parallel alignment with Ni (d) and antiparallel alignment for the high-doped Si (e). Elettra Highlights 2024–2025 35
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