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arXiv · 2510.03897

Adsorption-induced surface magnetism

Miloš Baljozović·Shiladitya Karmakar·André L. Fernandes Cauduro·Mothuku Shyam Sundar·Marco Lozano·Manish Kumar·Diego Soler Polo·Andreas K. Schmid·Ashutosh V. Bedekar·Pavel Jelinek·Karl-Heinz Ernst
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Abstract

We report the emergence of adsorption-induced magnetism from heterohelicene molecules on a non-magnetic Cu(100) surface. Spin-polarized low-energy electron microscopy (SP-LEEM) measurements reveal spin-dependent electron reflectivity for enantiopure 7,12,17-trioxa[11]helicene (TO[11]H) monolayers, indicating the formation of a spin-polarized state localized in the topmost copper layer. Control experiments on clean Cu(100) and TO[11]H on highly oriented pyrolytic graphite show no such effect, excluding artifacts and chirality-induced spin selectivity as origins. Spin-polarized density functional theory calculations with hybrid functionals attribute the magnetism to strong chemisorption, which induces hybridization between the molecular HOMO and copper s- and d-states, driving asymmetric spin-polarized charge redistribution at the interface. An extended Newns-Anderson-Grimley model incorporating on-site Coulomb repulsion in Cu d-orbitals reproduces the emergence of interfacial spin polarization above a threshold interaction strength, highlighting the key roles of hybridization parameters and Coulomb correlation. These findings reveal a mechanism for inducing magnetism at molecule-metal interfaces without inherently magnetic components, offering avenues for engineering spin-polarized states in organic-inorganic hybrid systems.

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Miloš Baljozović, Shiladitya Karmakar, André L. Fernandes Cauduro, Mothuku Shyam Sundar, Marco Lozano, Manish Kumar, Diego Soler Polo, Andreas K. Schmid, Ashutosh V. Bedekar, Pavel Jelinek, Karl-Heinz Ernst. 2025-10-04. Adsorption-induced surface magnetism. https://arxiv.org/abs/2510.03897

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