Substrate‐Independent Magnetic Bistability in Monolayers of the Single‐Molecule Magnet Dy<sub>2</sub>ScN@C<sub>80</sub> on Metals and Insulators

Krylov, Denis; Schimmel, Sebastian; Dubrovin, Vasilii; Liu, Fupin; Nguyen, T. T. Nhung; Spree, Lukas; Chen, Chia Hsiang; Velkos, Georgios; Bulbucan, Claudiu; Westerström, Rasmus; Studniarek, Michał; Dreiser, Jan; Heß, Christian; Büchner, B.; Avdoshenko, Stanislav M.; Popov, Alexey A.

doi:10.1002/anie.201913955

Cited by 30 publications

(41 citation statements)

References 76 publications

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“…This reflects the previously observed scatter in the adsorption geometry of Dy 2 @C 80 (CH 2 Ph) on graphene/Ir(111) due to its reduced value compared to 10 μ B per Dy 3+ ion in the single molecule. [28,38] In order to obtain more detailed information about the orientation of the magnetic moments in the sample we track the XMCD signal upon changing the angle between beam incidence and surface normal from θ = 0° (out-of-plane) to θ = 80° (grazing), see Figure 2b and Figure S2b, Supporting Information. Whereas the spectral shape does not change we observe a variation of the relative XMCD intensity between 50-60%.…”

Section: Resultsmentioning

confidence: 99%

Exceptionally High Blocking Temperature of 17 K in a Surface‐Supported Molecular Magnet

et al. 2021

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liquid-nitrogen temperature [3] or single atoms exhibiting extremely long magnetic relaxation times. [4][5][6] In particular, systems based on late lanthanide family elements, like Dy and Tb, have been largely in focus, including single-molecule, [2,3] singleatom, [4,5] or single-chain magnets. [7,8] Adsorption of SMMs on surfaces allows to study individual molecular units, as well as to realize transport schemes essential for the implementation of SMMs in molecular-scale spintronics or quantum computing devices. [9][10][11][12][13][14][15][16][17] However the transition from bulk to surface-supported systems often goes along with a substantial change or even loss of SMM properties, that is, magnetic moment, magnetic anisotropy, or magnetization behavior. [18][19][20][21] On metallic surfaces, the interaction of the magnetic moments with the surface is rather strong, which is evidenced by the observation of the Kondo effect. [22,23] Thus, benchmark measurements during the last years demonstrating magnetic bistability of surface-adsorbed SMMs have been reported on substrates, where molecules are electronically weakly coupled to -TbPc 2 on HOPG, [24] on MgO/Ag(100) [25] and on graphene/SiC, [26] pushing the blocking temperature (T B ) limit up to 9 K. On the other hand, DySc 2 N@C 80 monolayers on Au(111) [27] recently showed a hysteresis opening at temperatures up to 10 K. In this sense, lanthanide ions encaged in C 80 molecules reportedly outperform most SMMs by their combination of chemical robustness with slow magnetic relaxation. [27][28][29][30][31] To further push the magnetic lifetime in the monolayer regime two important criteria have to be fulfilled: the first requirement is to synthesize SMM compounds showing intrinsically high T B in the bulk. The second requires implementation of the appropriate methods for molecular deposition on substrates, which provide sufficient decoupling of the SMM from the surface.In this work we provide experimental evidence on outstanding slow magnetic relaxation in Dy 2 @C 80 (CH 2 Ph) sub-monolayers on a graphene/Ir(111) surface. The Dy 2 @C 80 (CH 2 Ph) molecules deposited by the electrospray deposition method are organized into islands as shown by low-temperature scanning tunneling microscopy (STM) imaging. We explore their magnetic properties by means of X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements. The analysis of the magnetic relaxation behavior of Dy 2 @C 80 (CH 2 Ph) adsorbed on graphene/Ir(111) yields a Single-molecule magnets (SMMs) are among the most promising building blocks for future magnetic data storage or quantum computing applications, owing to magnetic bistability and long magnetic relaxation times. The practical device integration requires realization of 2D surface assemblies of SMMs, where each magnetic unit shows magnetic relaxation being sufficiently slow at application-relevant temperatures. Using X-ray absorption spectroscopy and X-ray magnetic circular dichroism, it is shown that sub-monolayers of Dy ...

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Section: Resultsmentioning

confidence: 99%

Exceptionally High Blocking Temperature of 17 K in a Surface‐Supported Molecular Magnet

et al. 2021

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“…Strategies to preserve the SMMs properties include the decoupling between the SMM and a metallic surface, through the insertion of nonmagnetic insulator films [43]. Clearly then, the successful attempts in keeping the properties of SMMs when adsorbed on insulating films such as MgO [43,47], pose the question as whether the adsorption on bulk insulating surfaces represents a valid alternative to preserve the molecular magnetic properties of SMMs.…”

Section: Introductionmentioning

confidence: 99%

“…Magnetic networks on bulk insulating surfaces are expected to have advantages over metallic substrates: for example, magnetic moments and hysteresis cycles might not be affected or quenched by the substrate-molecule (S-M) electronic hybridization [43,47,50,51]. A second advantage is that due the weaker reactivity of insulators as compared to metals [50][51][52][53], the S-M interaction prevents drastic changes in the structural, and thus electronic and magnetic properties of the molecule [50,51].…”

Section: Introductionmentioning

confidence: 99%

Magnetic Energy Landscape of Dimolybdenum Tetraacetate on a Bulk Insulator Surface

Cococcioni

Floris

2021

Applied Sciences

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The magnetic states and the magnetic anisotropy barrier of a transition metal molecular complex, dimolybdenum tetraacetate, are investigated via density functional theory (DFT). Calculations are performed in the gas phase and on a calcite (10.4) bulk insulating surface, using the Generalized-Gradient Approximation (GGA)-PBE and the Hubbard-corrected DFT + U and DFT + U + V functionals. The molecular complex (denoted MoMo) contains two central metallic molybdenum atoms, embedded in a square cage of acetate groups. Recently, MoMo was observed to form locally regular networks of immobile molecules on calcite (10.4), at room conditions. As this is the first example of a metal-coordinated molecule strongly anchored to an insulator surface at room temperature, we explore here its magnetic properties with the aim to understand whether the system could be assigned features of a single molecule magnet (SMM) and could represent the basis to realize stable magnetic networks on insulators. After an introductory review on SMMs, we show that, while the uncorrected GGA-PBE functional stabilizes MoMo in a nonmagnetic state, the DFT + U and DFT + U + V approaches stabilize an antiferromagnetic ground state and several meta-stable ferromagnetic and ferrimagnetic states. Importantly, the energy landscape of magnetic states remains almost unaltered on the insulating surface. Finally, via a noncollinear magnetic formalism and a newly introduced algorithm, we calculate the magnetic anisotropy barrier, whose value indicates the stability of the molecule’s magnetic moment.

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“…The measurements of the evaporated sub-monolayer are from ref. [22] . XAS studies of Dy 2 ScN-SAM were performed at the UE46_PGM-1 beamline [19] at BESSY II (Helmholtz-Zentrum Berlin) and the X-Treme beamline at the Swiss Light Source (Paul Scherrer Institute).…”

Section: Doi: 101002/advs202000777mentioning

confidence: 99%

Magnetic Hysteresis at 10 K in Single Molecule Magnet Self‐Assembled on Gold

et al. 2021

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Tremendous progress in the development of single molecule magnets (SMMs) raises the question of their device integration. On this route, understanding the properties of low‐dimensional assemblies of SMMs, in particular in contact with electrodes, is a necessary but difficult step. Here, it is shown that fullerene SMM self‐assembled on metal substrate from solution retains magnetic hysteresis up to 10 K. Fullerene‐SMM DySc2N@C80 and Dy2ScN@C80 are derivatized to introduce a thioacetate group, which is used to graft SMMs on gold. Magnetic properties of grafted SMMs are studied by X‐ray magnetic circular dichroism and compared to the films of nonderivatized fullerenes prepared by sublimation. In self‐assembled films, the magnetic moments of the Dy ions are preferentially aligned parallel to the surface, which is different from the disordered orientation of endohedral clusters in nonfunctionalized fullerenes. Whereas chemical derivatization reduces the blocking temperature of magnetization and narrows the hysteresis of Dy2ScN@C80, for DySc2N@C80 equally broad hysteresis is observed as in the fullerene multilayer. Magnetic bistability in the DySc2N@C80 grafted on gold is sustained up to 10 K. This study demonstrates that self‐assembly of fullerene‐SMM derivatives offers a facile solution‐based procedure for the preparation of functional magnetic sub‐monolayers with excellent SMM performance.

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Substrate‐Independent Magnetic Bistability in Monolayers of the Single‐Molecule Magnet Dy₂ScN@C₈₀ on Metals and Insulators

Cited by 30 publications

References 76 publications

Exceptionally High Blocking Temperature of 17 K in a Surface‐Supported Molecular Magnet

Exceptionally High Blocking Temperature of 17 K in a Surface‐Supported Molecular Magnet

Magnetic Energy Landscape of Dimolybdenum Tetraacetate on a Bulk Insulator Surface

Magnetic Hysteresis at 10 K in Single Molecule Magnet Self‐Assembled on Gold

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Substrate‐Independent Magnetic Bistability in Monolayers of the Single‐Molecule Magnet Dy2ScN@C80 on Metals and Insulators

Cited by 30 publications

References 76 publications

Exceptionally High Blocking Temperature of 17 K in a Surface‐Supported Molecular Magnet

Exceptionally High Blocking Temperature of 17 K in a Surface‐Supported Molecular Magnet

Magnetic Energy Landscape of Dimolybdenum Tetraacetate on a Bulk Insulator Surface

Magnetic Hysteresis at 10 K in Single Molecule Magnet Self‐Assembled on Gold

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Substrate‐Independent Magnetic Bistability in Monolayers of the Single‐Molecule Magnet Dy₂ScN@C₈₀ on Metals and Insulators