| 1. |
- Azimi Mousolou, Vahid, et al.
(författare)
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Transmon probe for quantum characteristics of magnons in antiferromagnets
- 2023
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 108:9
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Tidskriftsartikel (refereegranskat)abstract
- The detection of magnons and their quantum properties, especially in antiferromagnetic (AFM) materials, is a substantial step to realize many ambitious advances in the study of nanomagnetism and the development of energy efficient quantum technologies. The recent development of hybrid systems based on superconducting circuits provides the possibility to engineer quantum sensors that exploit different degrees of freedom. Here, we examine the magnon-photon-transmon hybridization based on bipartite AFM materials, which gives rise to an effective coupling between a transmon qubit and magnons in a bipartite AFM. We demonstrate how magnon modes, their chiralities, and quantum properties, such as nonlocality and two-mode magnon entanglement in bipartite AFMs, can be characterized through the Rabi frequency of the superconducting transmon qubit.
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| 2. |
- Liu, Yuefei, et al.
(författare)
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Tunable phonon-driven magnon-magnon entanglement at room temperature
- 2023
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Ingår i: New Journal of Physics. - : IOP Publishing Ltd. - 1367-2630. ; 25:11
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Tidskriftsartikel (refereegranskat)abstract
- We report the existence of entangled steady-states in bipartite quantum magnonic systems at elevated temperatures. We consider dissipative dynamics of two magnon modes in a bipartite antiferromagnet, subjected to interaction with a phonon mode and an external rotating magnetic field. To quantify the bipartite magnon-magnon entanglement, we use entanglement negativity and compute its dependence on temperature and magnetic field. We provide evidence that the coupling between magnon and phonon modes is necessary for the entanglement, and that, for any given phonon frequency and magnon-phonon coupling rate, there are always ranges of the magnetic field amplitudes and frequencies for which magnon-magnon entanglement persists at room temperature.
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| 3. |
- Lu, Zhiwei, et al.
(författare)
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Influence of nonlocal damping on magnon properties of ferromagnets
- 2023
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 108:1
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Tidskriftsartikel (refereegranskat)abstract
- We study the influence of nonlocal damping on the magnon properties of Fe, Co, Ni, and Fe1-xCox (x=30%,50%) alloys. The Gilbert damping parameter is typically considered as a local scalar both in experiment and in theoretical modeling. However, recent works have revealed that Gilbert damping is a nonlocal quantity that allows for energy dissipation between atomic sites. With the Gilbert damping parameters calculated from a state-of-the-art real-space electronic structure method, magnon lifetimes are evaluated from spin dynamics and linear response, where a good agreement is found between these two methods. It is found that nonlocal damping affects the magnon lifetimes in different ways depending on the system. Specifically, we find that in Fe, Co, and Ni, the nonlocal damping decreases the magnon lifetimes, while in Fe70Co30 and Fe50Co50 an opposite, nonlocal damping effect is observed, and our data show that it is much stronger in the former.
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| 4. |
- Maciel, Renan P., et al.
(författare)
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Resistive switching in graphene : A theoretical case study on the alumina-graphene interface
- 2023
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Ingår i: Physical Review Research. - : American Physical Society. - 2643-1564. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- Neuromorphic computing mimics the brain's architecture to create energy-efficient devices. Reconfigurable synapses are crucial for neuromorphic computing, which can be achieved through memory-resistive (memristive) switching. Graphene-based memristors have shown nonvolatile multibit resistive switching with desirable endurance. Through first-principles calculations, we study the structural and electronic properties of graphene in contact with an ultra-thin alumina overlayer and demonstrate how one can use charge doping to exert direct control over its interfacial covalency, reversibly switching between states of conductivity and resistivity in the graphene layer. We further show that this proposed mechanism can be stabilized through the p-type doping of graphene, e.g., by naturally occurring defects, the passivation of dangling bonds or defect engineering.
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| 5. |
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| 6. |
- Xu, Qichen, et al.
(författare)
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Metaheuristic conditional neural network for harvesting skyrmionic metastable states
- 2023
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Ingår i: Physical Review Research. - : American Physical Society. - 2643-1564. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- We present a metaheuristic conditional neural-network-based method aimed at identifying physically interest-ing metastable states in a potential energy surface of high rugosity. To demonstrate how this method works, we identify and analyze spin textures with topological charge Q ranging from 1 to -13 (where antiskyrmions have Q < 0) in the Pd/Fe/Ir(111) system, which we model using a classical atomistic spin Hamiltonian based on parameters computed from density functional theory. To facilitate the harvest of relevant spin textures, we make use of the newly developed segment anything model. Spin textures with Q ranging from -3 to -6 are further analyzed using finite-temperature spin-dynamics simulations. We observe that for temperatures up to around 20 K, lifetimes longer than 200 ps are predicted, and that when these textures decay, new topological spin textures are formed. We also find that the relative stability of the spin textures depend linearly on the topological charge, but only when comparing the most stable antiskyrmions for each topological charge. In general, the number of holes (i.e., non-self-intersecting curves that define closed domain walls in the structure) in the spin texture is an important predictor of stability-the more holes, the less stable the texture. Methods for systematic identification and characterization of complex metastable skyrmionic textures-such as the one demonstrated here-are highly relevant for advancements in the field of topological spintronics.
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