Controlling the Exchange Field of Surface Spin Impurities via DC Voltages
Xue Zhang, José Reina Gálvez, Wu, Di'an, J. Martinek, Andreas J. Heinrich, Taeyoung Choi, Christoph Wolf · arXiv (Cornell University) · 2024
Recent advances in scanning tunneling microscopy have enabled quantum-coherent control of single surface spins via all-electric electron spin resonance (ESR). Such control requires magnetoelectric coupling, since spin resonance is a magnetic effect. We show that a magnetic tip induces a bias-dependent exchange field on a localized Anderson impurity via virtual particle exchange with the magnetic lead. This field differs from Heisenberg exchange and can be tuned, reversed, or suppressed by the bias voltage. Our model reproduces bias-controlled resonance shifts for S = 1/2 titanium atoms and Fe(II) phthalocyanine, enabling spin control via the exchange field and revealing the magnetoelectric mechanism behind all-electric ESR for spin-based quantum technologies.