Magnetic Dimer Entanglement Can Now Be Switched on and Off Electrically

Yuefei Liu and colleagues at Uppsala University, in collaboration with AlbaNova University, Chinese Academy of Sciences, Swedish e-Science Research Centre (SeRC), and KTH Royal Institute of Technology, have identified quantum corrections to the Gilbert damping mechanism through ferroelectric control of a magnetic dimer. Their ab initio calculations and quantum simulations reveal that switching the ferroelectric polarisation alters the magnetic exchange interaction, offering a means to manipulate and diagnose entanglement dynamics via measurable magnetisation traces. This minimal, non-volatile platform provides a key link between theoretical modelling and experimental observation, potentially enabling voltage-controlled quantum entanglement within magnetic spin networks Ferroelectric control of magnetic dimer exchange interactions for quantum damping studies The technique central to discerning quantum from classical Gilbert spin damping relies on carefully controlling magnetic dimer interactions using ferroelectric polarisation switching. Ferroelectricity, a property exhibited by certain materials allowing for switchable electrical polarisation, acts as a remote control for magnetism. Magnetic dimers, consisting of pairs of magnetic atoms, were constructed on a ferroelectric substrate, with materials selected to ensure reversing the substrate’s polarisation fundamentally alters the exchange interaction between the atoms. This alteration shifts the alignment from ferromagnetic, where the magnetic moments align parallel to each other, to antiferromagnetic, where they align antiparallel, akin to linking two coins so they always land on opposite sides. Understanding the interplay between these alignments is crucial for controlling spin dynamics. Detailed ab initio calculations, constructing a model based on fundamental physical laws without empirical parameters, mapped how this polarisation change affects the dimer’s magnetic behaviour, providing a theoretical framework for interpreting experimental observations. Researchers investigated magnetic dimers placed on a ferroelectric substrate to explore quantum effects in Gilbert spin damping, a process describing the dissipation of energy in magnetic materials. Ab initio calculations revealed that reversing the polarisation of the substrate switches the interaction between the atoms, moving it between ferromagnetic and antiferromagnetic alignment. This control arises from changes in charge distribution and orbital hybridisation at the interface between the magnetic dimer and the ferroelectric substrate, influencing the overlap of atomic orbitals and thus the strength and sign of the exchange interaction. Calculations employed a plane-wave energy cut-off of 400 eV, ensuring sufficient accuracy in describing the electronic structure, and a 3x3x1 k-point mesh for sampling the Brillouin zone, while a 5x5x1 supercell of In2Se3 was used to isolate dimer interactions and minimise spurious interactions between periodic images. This approach offers a non-volatile method to control magnetism, differing from techniques utilising mechanical or optical actuation, which often require continuous energy input, and the work offers a key pathway towards experimentally verifying quantum effects in magnetism, which are often masked by classical behaviour.

Ferroelectric Polarity Reversal Controls Magnetic Dimer Entanglement and Gilbert Damping A magnetization change of -0.054 eÅ/u.c. signifies, for the first time, ferroelectric control over magnetic dimer entanglement. Previously, verifying quantum corrections to Gilbert damping, the mechanism by which magnetic spins lose energy and ultimately reach equilibrium, remained experimentally impossible due to the subtle nature of these effects and the difficulty in isolating them from classical contributions. These findings demonstrate a minimal, non-volatile platform connecting theoretical modelling with observable magnetic behaviour. This enables the distinction between quantum and classical Gilbert spin damping via manipulation of a magnetic dimer’s interaction. Ab initio calculations reveal that reversing the ferroelectric polarisation switches the inter-spin exchange, shifting it between ferromagnetic and antiferromagnetic states, which is vital for manipulating entanglement dynamics, a key resource in quantum information processing. Switching between ferromagnetic and antiferromagnetic regimes, achieved via ferroelectric control of a magnetic dimer, allows distinction between quantum and classical Gilbert spin damping. Simulations utilising a quantum Landau-Lifshitz-Gilbert equation, a theoretical framework describing the time evolution of magnetic moments, revealed a link between drops in net magnetisation and rises in entanglement. The von Neumann entropy, a measure of quantum entanglement, reached a maximum value of 2.32 in the dimer system. A magnetization-based diagnostic links magnetisation traces to entanglement dynamics, enabling electrical control of dimer entanglement. This minimal platform connects modelling to experimentally accessible observations and provides a basis for voltage-controlled quantum entanglement in magnetic spin networks, potentially leading to new avenues for spintronic devices and quantum technologies. The ability to electrically control entanglement offers significant advantages over traditional methods relying on magnetic fields or optical excitation. Ferroelectric control of magnetic dimers as a route to verifying quantum Gilbert damping Despite advances in understanding magnetic materials, definitively identifying quantum effects within the Gilbert damping mechanism has proven remarkably difficult. Ways to distinguish these subtle “quantum corrections” from classical behaviour have long been sought, but experimental proof has remained elusive. The challenge lies in the fact that quantum effects are often weak and easily obscured by thermal fluctuations and other classical processes. The current study relies heavily on simulations and ab initio calculations, yet proposes a method utilising ferroelectric control of magnetic dimers, offering a potential diagnostic tool. The use of a ferroelectric substrate provides a means to isolate and amplify these quantum effects, making them more readily observable.

This research successfully demonstrates a method for manipulating entanglement within magnetic materials using ferroelectric polarisation, creating a platform to connect theoretical modelling with measurable magnetic behaviour. By controlling the interaction between atoms in a magnetic dimer, scientists can switch between ferromagnetic and antiferromagnetic alignments via an external electric field. This offers a pathway towards voltage-controlled quantum entanglement, potentially simplifying future spintronic devices by reducing the energy consumption and increasing the speed of operation. The ability to manipulate dimer alignment via electric field provides a novel route for exploring quantum phenomena in magnetism and could lead to advancements in data storage technologies, potentially enabling the development of more efficient and compact memory devices. Further research will focus on extending this approach to larger magnetic systems and exploring the potential for creating complex entangled states. The research successfully demonstrated ferroelectric control of entanglement within a magnetic dimer, switching its alignment between ferromagnetic and antiferromagnetic states via an external electric field. This provides a means to distinguish between quantum and classical Gilbert spin damping, a long-sought goal in understanding magnetic materials. By linking theoretical modelling to experimentally accessible magnetic behaviour, the study offers a platform for investigating quantum phenomena. The authors intend to extend this approach to larger magnetic systems and explore the creation of more complex entangled states. 👉 More information🗞 Ferroelectrical Switching as a Probe of Quantum Damping in Magnetic Spin Systems🧠 ArXiv: https://arxiv.org/abs/2606.07378 Stay current. See today’s quantum computing news on Quantum Zeitgeist for the latest breakthroughs in qubits, hardware, algorithms, and industry deals. Tags: