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arXiv · 2512.09320

Low-dimensionality-induced tunable ferromagnetism in SrRuO$_3$ ultrathin films

Jinyoung Kim·Minjae Kim·Donghan Kim·Sungsoo Hahn·Younsik Kim·Minsoo Kim·Byungmin Sohn·Changyoung Kim
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Abstract

Quantum materials near electronic or magnetic phase boundaries exhibit enhanced tunability, as their emergent properties become highly sensitive to external perturbations. Here, we demonstrate precise control of ferromagnetism in a SrRuO$_3$ ultrathin film, where a high density of states (DOS), arising from low-dimensional quantum states, places the system at the crossover between a non-magnetic and bulk ferromagnetic state. Using spin- and angle-resolved photoemission spectroscopy (SRPES/ARPES), transport measurements, and theoretical calculations, we systematically tune the Fermi level via electron doping across the high-DOS point. We directly visualize the spin-split band structure and reveal its influence on both magnetic and transport properties. Our findings provide compelling evidence that magnetism can be engineered through DOS control at a phase crossover, establishing a pathway for the rational design of tunable quantum materials.

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Jinyoung Kim, Minjae Kim, Donghan Kim, Sungsoo Hahn, Younsik Kim, Minsoo Kim, Byungmin Sohn, Changyoung Kim. 2025-12-10. Low-dimensionality-induced tunable ferromagnetism in SrRuO$_3$ ultrathin films. https://doi.org/10.1021/acs.nanolett.5c05253

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