A gateway towards non-collinear spin processing using three-atom magnets with strong substrate coupling

Hermenau, Jan; Ibañez-Azpiroz, Julen; Hübner, Chr.; Sonntag, A.; Baxevanis, B.; Ton, K. T.; Steinbrecher, Manuel; Khajetoorians, Alexander A.; Dias, Manuel dos Santos; Blügel, Stefan; Wiesendanger, R.; Lounis, Samir; Wiebe, Jens

doi:10.1038/s41467-017-00506-7

Cited by 32 publications

(54 citation statements)

References 51 publications

(94 reference statements)

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“…This play-ground is particularly attractive given that several STM experiments have reported clear observations of stable magnetic moments in this type of composite system (see e.g., Refs. [112,63,113]). This strongly suggests that local fluctuation effects decrease with increasing cluster size, a feature that is in qualitative accordance with one main finding presented throughout the review, namely that the relative impact of the fluctuations becomes smaller the larger the magnetic moment gets.…”

Section: Discussionmentioning

confidence: 99%

Spin-fluctuation and spin-relaxation effects of single adatoms from first principles

Ibañez-Azpiroz

Dias

Blügel

et al. 2018

J. Phys.: Condens. Matter

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Single adatoms offer an exceptional playground for studying magnetism and its associated dynamics at the atomic scale. Here we review recent results on single adatoms deposited on metallic substrates, based on time-dependent density functional theory. First we analyze quantum zero-point spin-fluctuations (ZPSF) as calculated from the fluctuation-dissipation theorem, and show how they affect the magnetic stability by modifying the magnetic anisotropy energy. We also assess the impact of ZPSF in the limit of small hybridization to the substrate characteristic of semi-insulating substrates, connecting to recent experimental investigations where magnetic stability of a single adatom was achieved for the first time. Secondly, we inspect further the dynamics of single adatoms by considering the longitudinal and transverse spin-relaxation processes, whose time-scales are analyzed and related to the underlying electronic structure of both the adatom and the substrate. Thirdly, we analyze spin-fluctuation modes of paramagnetic adatoms, i.e. adatoms where the Stoner criterion for magnetism is almost fulfilled. Interestingly, such modes can develop well-defined peaks in the meV range, their main characteristics being determined by two fundamental electronic properties, namely the Stoner parameter and the density of states at the Fermi level. Furthermore, simulated inelastic scanning tunneling spectroscopy curves reveal that these spin-fluctuation modes can be triggered by tunneling electrons, opening up potential applications also for paramagnetic adatoms. Lastly, an overview of the outstanding issues and future directions is given.

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Section: Discussionmentioning

confidence: 99%

Spin-fluctuation and spin-relaxation effects of single adatoms from first principles

Ibañez-Azpiroz

Dias

Blügel

et al. 2018

J. Phys.: Condens. Matter

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“…Ref. [15]. The cleaned Pt(111) surface was coated with a fraction of a monolayer Co resulting in monolayer islands and stripes (see Supplementary Note 1) before single Fe atoms were deposited on the pre-cooled sample leading to a statistical distribution of Fe atoms on the Pt terraces.…”

Section: Methodsmentioning

confidence: 99%

Long Spin-Relaxation Times in a Transition-Metal Atom in Direct Contact to a Metal Substrate

et al. 2018

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Long spin-relaxation times are a prerequisite for the use of spins in data storage or nanospintronics technologies. An atomic-scale solid-state realization of such a system is the spin of a transition-metal atom adsorbed on a suitable substrate. For the case of a metallic substrate, which enables the direct addressing of the spin by conduction electrons, the experimentally measured lifetimes reported to date are on the order of only hundreds of femtoseconds. Here, we show that the spin states of iron atoms adsorbed directly on a conductive platinum substrate have a surprisingly long spin-relaxation time in the nanosecond regime, which is comparable to that of a transition metal atom decoupled from the substrate electrons by a thin decoupling layer. The combination of long spin-relaxation times and strong coupling to conduction electrons implies the possibility to use flexible coupling schemes to process the spin information.

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“…This surprising finding was rationalized in terms of an Dzyaloshinskii-Moriya-enhanced Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. 14 These earlier results obtained on MnO 2 /Ir(001) showed that this indirect magnetic coupling mechanism which was previously only observed for assemblies of single atoms or clusters on Pt(111) surfaces 15,16 can also result in chiral magnetic order in laterally extended structures.…”

Section: Introductionmentioning

confidence: 85%

Structural and magnetic properties of 3d transition metal oxide chains on the (001) surfaces of Ir and Pt

et al. 2019

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We present a survey of the structural and magnetic properties of submonolayer transition metal dioxides on the (001) surfaces of the heavy face-centered cubic (fcc) noble metals Ir and Pt performed by spin-averaged scanning tunneling microscopy (STM) and spin-polarized (SP-)STM. Our STM results confirm that deposition of Co, Fe, Mn, and Cr on the (2 × 1) oxygen-reconstructed Ir(001) surface leads to the formation of quasi one-dimensional chains with a (3 × 1) unit cell. As recently predicted by density functional theory [Ferstl et al., Phys. Rev. Lett. 117, 046101 (2016)], our SP-STM images of FeO2 and MnO2 on Ir(001) show a two-fold periodicity along the chains which is characteristic for an antiferromagnetic coupling along the chains. In addition, these two materials also exhibit spontaneous, permanent, and long-range magnetic coupling across the chains. Whereas we find a ferromagnetic inter-chain coupling for FeO2/Ir(001), the magnetic coupling of MnO2 on Ir(001) appears to be a non-collinear 120 • spin spiral, resulting in a (9 × 2) magnetic unit cell. On Pt(001) patches of (3 × 1)-reconstructed oxide chains could only be prepared by transition metal (Co, Fe, and Mn) deposition onto the cold substrate and subsequent annealing in an oxygen atmosphere. Again SP-STM on MnO2/Pt(001) reveals a very large, (15 × 2) magnetic unit cell which can tentatively be explained by a commensurate 72 • spin spiral. Large scale SP-STM images reveal a long wavelength spin rotation along the MnO2 chain.

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A gateway towards non-collinear spin processing using three-atom magnets with strong substrate coupling

Cited by 32 publications

References 51 publications

Spin-fluctuation and spin-relaxation effects of single adatoms from first principles

Spin-fluctuation and spin-relaxation effects of single adatoms from first principles

Long Spin-Relaxation Times in a Transition-Metal Atom in Direct Contact to a Metal Substrate

Structural and magnetic properties of 3d transition metal oxide chains on the (001) surfaces of Ir and Pt

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