Critical temperature of two-dimensional hydrogenated multilayer graphene-based diluted ferromagnet

Szałowski, K.

doi:10.1016/j.carbon.2016.07.024

Cited by 5 publications

(5 citation statements)

References 58 publications

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“…⁄ can describe our scaling data quite well. We notice this fits the theoretical prediction for the case that magnetic moments are only on one set of graphene sublattices [38]. Even though our experimental condition is definitely different from the premise of ref.…”

Section: Resultssupporting

confidence: 88%

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Evidence of tunable magnetic coupling in hydrogenated graphene

Cao

Tian

et al. 2020

Phys. Rev. B

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A lot of efforts have been devoted to understanding the origin and effects of magnetic moments induced in graphene with carbon atom vacancy, or light adatoms like hydrogen or fluorine. At the meantime, the large negative magnetoresistance (MR) widely observed in these systems is not well understood, nor had it been associated with the presence of magnetic moments. In this paper, we study the systematic evolution of the large negative MR of in-situ hydrogenated graphene in ultra-high vacuum (UHV) environment. We find for most combination of electron density (ne) and hydrogen density (nH), MR at different temperature can be scaled to 𝛼𝛼 = 𝜇𝜇 𝐵𝐵 𝐵𝐵 𝑘𝑘 𝐵𝐵 (𝑇𝑇 − 𝑇𝑇 * ) ⁄ , where T * is the Curie-Weiss temperature. The sign of T * indicates the existence of tunable ferromagnetic-like (T * >0) and anti-ferromagnetic-like (T * <0) coupling in hydrogenated graphene. However, the lack of hysteresis of MR or anomalous Hall effect below |T * | points to the fact that long-range magnetic order did not emerge, which we attribute to the competition of different magnetic orders and disordered arrangement of magnetic moments on graphene. We also find that localized impurity states introduced by H adatoms could modify the capacitance of hydrogenated graphene. This work provides a new way to extract information from large negative MR behavior and can be a key to help understanding interactions of magnetic moments in graphene.

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Section: Resultssupporting

confidence: 88%

“…Even though our experimental condition is definitely different from the premise of ref. [38], the surprising agreement might indicate the emergence of FM-like coupling and it might point to something deeper than a mere coincidence. Clearly, more theoretical work is required to explain our experimental observation.…”

Section: Resultsmentioning

confidence: 98%

Evidence of tunable magnetic coupling in hydrogenated graphene

Cao

Tian

et al. 2020

Phys. Rev. B

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“…s ¼ −Js • S, between the itinerant electron spin s and the impurity 1=2-spin S [31], and (2) local spin orbit coupling (SOC) in the vicinity of an adatom [50,[55][56][57]71,72]. To be specific, we use hydrogen and fluorine adatoms, both of which induce sizable SOC enhancements [55,56] and can also carry magnetic moments [73][74][75][76][77][78][79][80]. We also assume low concentrations η (per carbon atom) of dilute spin-active impurities [81] for the independent scatter picture to be valid.…”

mentioning

confidence: 99%

Spin Relaxation ins-Wave Superconductors in the Presence of Resonant Spin-Flip Scatterers

et al. 2020

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Employing analytical methods and quantum transport simulations we investigate the relaxation of quasiparticle spins in graphene proximitized by an s-wave superconductor in the presence of resonant magnetic and spin-orbit active impurities. Off resonance, the relaxation increases with decreasing temperature when electrons scatter off magnetic impurities-the Hebel-Slichter effect-and decreases when impurities have spin-orbit coupling. This distinct temperature dependence (not present in the normal state) uniquely discriminates between the two scattering mechanisms. However, we show that the Hebel-Slichter picture breaks down at resonances. The emergence of Yu-Shiba-Rusinov bound states within the superconducting gap redistributes the spectral weight away from magnetic resonances. The result is opposite to the Hebel-Slichter expectation: the spin relaxation decreases with decreasing temperature. Our findings hold for generic s-wave superconductors with resonant magnetic impurities, but also, as we show, for resonant magnetic Josephson junctions.

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“…This trend in less negative Weiss temperature with more complex Co moiety indicates that graphene sublattices with the Co atoms experience increasingly strong ferromagnetic exchange, while otherwise, antiferromagnetic exchange is present in the rest of the system, as proposed in a model of hydrogenated graphene. [ 40 ] Overall, this yields a canted spin structure with a measured magnetization that presents a ferromagnetic response (e.g., M ( µ 0 H, T ) with hysteresis). A detailed description of the mechanisms responsible is discussed below.…”

Section: Resultsmentioning

confidence: 99%

Robust Room Temperature Ferromagnetism In Cobalt Doped Graphene by Precision Control of Metal Ion Hybridization

Paidi

Jung

Lee

et al. 2022

Adv Funct Materials

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Graphene-based magnetic materials exhibit novel properties and promising applications in the development of next-generation spintronic devices. Modern synthesis techniques have paved the way to design precisely the local environments of metal atoms anchored onto a nitrogen-doped graphene matrix. Herein, it is demonstrated that grafting cobalt (Co) into the graphene lattice induces robust and stable room-temperature ferromagnetism. These comprehensive experiments and first-principles calculations unambiguously identify that the mechanism for this unusual ferromagnetism is π-d orbital hybridization between Co d xz and graphene p z orbitals. Here, it is found that the magnetic interactions of Co-carbon ions are mediated by the spinpolarized graphene p z orbitals, and room temperature ferromagnetism can be stabilized by electron doping. It is also found that the electronic structure near the Fermi level, which sets the nature of spin polarization of graphene p z bands, strongly depends on the local environment of the Co moiety. This is the crucial, previously missing, ingredient that enables control of the magnetism. Overall, these observations unambiguously reveal that engineering the atomic structure of metal-embedded graphene lattices through careful d to p orbital interactions opens a new window of opportunities for developing graphene-based spintronics devices.

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Critical temperature of two-dimensional hydrogenated multilayer graphene-based diluted ferromagnet

Cited by 5 publications

References 58 publications

Evidence of tunable magnetic coupling in hydrogenated graphene

Evidence of tunable magnetic coupling in hydrogenated graphene

Spin Relaxation ins-Wave Superconductors in the Presence of Resonant Spin-Flip Scatterers

Robust Room Temperature Ferromagnetism In Cobalt Doped Graphene by Precision Control of Metal Ion Hybridization

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