Insulator at the Ultrathin Limit: MgO on Ag(001)

Schintke, Silvia; Messerli, Stéphane; Pivetta, Marina; Patthey, F.; Libioulle, Laurent; Stengel, Massimiliano; Vita, Alessandro De; Schneider, W. D.

doi:10.1103/physrevlett.87.276801

Cited by 325 publications

(385 citation statements)

References 36 publications

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“…The epitaxial MgO layers were grown by sublimation of Mg in O 2 atmosphere (10 −6 mbar) while keeping the sample at 625 K. [ 19 ] A submonolayer of TbPc 2 was sublimed at 650 K at a rate of ≈0.1 ML min -1 onto the surface kept at room temperature. The multilayer sample was prepared by sublimation of ≈3 ML of TbPc 2 onto MgO/Ag(100).…”

Section: Methodsmentioning

confidence: 99%

“…We use nonmagnetic, insulating MgO, wellknown in inorganic spintronic applications, [ 17,18 ] which allows to control the electron tunneling rate over many orders of magnitude. [ 19 ] Moreover, we employ the TbPc 2 SMM [ 14,15,[20][21][22][23] as a model system. In the neutral molecule, the Tb(III) ion exhibits an electronic spin state of J = 6.…”

Section: Doi: 101002/adma201506305mentioning

confidence: 99%

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Giant Hysteresis of Single‐Molecule Magnets Adsorbed on a Nonmagnetic Insulator

et al. 2016

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metal electrode. We use nonmagnetic, insulating MgO, wellknown in inorganic spintronic applications, [ 17,18 ] which allows to control the electron tunneling rate over many orders of magnitude. [ 19 ] Moreover, we employ the TbPc 2 SMM [ 14,15,[20][21][22][23] as a model system. In the neutral molecule, the Tb(III) ion exhibits an electronic spin state of J = 6. It is sandwiched between two phthalocyanine (Pc) macrocycles (cf. schematic view in Figure 1 a) hosting an unpaired electron delocalized over the Pc ligands. The easy-axis-type magnetic anisotropy imposes an energy barrier of ≈65 meV for magnetization reversal, [ 23 ] which is largest within the whole series of lanthanide-Pc 2 SMMs. [ 14,15 ] On nonmagnetic conducting substrates, only vanishing remanence [6][7][8][9][10] and very narrow hysteresis loops [6][7][8][9] were observed, much smaller than in bulk measurements, [ 20 ] illustrating the disruptive effects of the surface. We note that the adsorption of TbPc 2 on (anti)ferromagnetic materials represents a different situation because of the magnetic exchange interaction with the substrate. [ 24,25 ] In those cases, the SMMs were not shown to exhibit slow relaxation of magnetization. Rather, the hysteresis is linked to the one of the magnetic substrates, i.e., it is not an intrinsic property of the SMMs. Overall, the detailed knowledge on TbPc 2 makes it an ideal candidate to test if a tunnel barrier can boost the magnetic properties of surface-adsorbed SMMs. In this communication we show that the magnetic remanence and hysteresis opening obtained with TbPc 2 on MgO tunnel barriers outperform the ones of any other surface-adsorbed SMM [4][5][6][7][8][9][10][11][12][13]26 ] as well as those of bulk samples of TbPc 2 . [ 20 ] The scanning tunneling microscopy (STM) images in Figure 1 b,c show that TbPc 2 self-assembles by forming perfectly ordered 2D islands on two monolayers (MLs) of MgO on Ag(100). In line with former results, the SMMs are adsorbed fl at on the surface (cf. discussion of our STM and X-ray linear dichroism (XLD) data below). [ 6,27 ] This excludes that the extraordinary magnetic properties observed in this study are due to upstanding molecules having their macrocycles perpendicular to the surface, which would lead to a reduced interaction of the Tb(III) ion with the surface. The high-resolution image in Figure 1 c reveals eight lobes per molecule, reminiscent of the staggered conformation of the two phthalocyanine ligands. [ 27 ] Islands with the identical molecular assembly are formed by TbPc 2 adsorbed directly onto Ag(100), as shown in the Supporting Information.The magnetic properties of the Tb(III) ions in the surfaceadsorbed SMMs are determined by X-ray magnetic circular dichroism (XMCD) measurements at the M 4,5 (3 d → 4 f ) edges of Tb. For sub-MLs of TbPc 2 on MgO we fi nd a strong remanence larger than 40% of the saturation magnetization sat M and Single-molecule magnets (SMMs) [ 1 ] are very promising for molecular spintronics [ 2 ] and quantum information processing, [...

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Section: Methodsmentioning

confidence: 99%

Section: Doi: 101002/adma201506305mentioning

confidence: 99%

Giant Hysteresis of Single‐Molecule Magnets Adsorbed on a Nonmagnetic Insulator

et al. 2016

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“…16 Gold is evaporated from a high-purity wire wrapped around a tungsten filament onto the cryogenic sample. Subsequent annealing to 150 K induces the development of planar, beltlike Au islands of ϳ2 nm width and up to 50 nm length ͓Fig.…”

Section: Methodsmentioning

confidence: 99%

Characterizing low-coordinated atoms at the periphery of MgO-supported Au islands using scanning tunneling microscopy and electronic structure calculations

et al. 2010

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The perimeter of oxide-supported metal particles is suggested to be of pivotal importance for various catalytic processes. To elucidate the underlying effects, the electronic properties of edge and corner atoms of planar Au clusters on MgO/Ag͑001͒ thin films have been analyzed with scanning tunneling microscopy and electronic structure calculations. The low-coordinated perimeter atoms are characterized by a high density of s-derived states at the Fermi level. Those states accommodate transfer electrons from the MgO/Ag substrate, which render the perimeter atoms negatively charged. In contrast, the inner atoms of the island are not affected by the charge transfer and remain neutral. This combination of charge accumulation and high state-density explains the specific relevance of the cluster perimeter in adsorption and reaction processes.

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“…While MIGS have been reported in MgO/Cu(222) 10 or MgO/Ag(001) 11 , the question of whether the observed gap states are formed by local chemical bonding remained, since MgO(222) is a polar surface so that a strong hybridization between the O 2p band and the Ag 5sp band is expected for MgO/Ag 13 .…”

Section: Introductionmentioning

confidence: 99%

Electronic properties of metal-induced gap states at insulator/metal interfaces: Dependence on the alkali halide and the possibility of excitonic mechanism of superconductivity

et al. 2004

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Motivated from the experimental observation of metal induced gap states (MIGS) at insulator/metal interfaces by Kiguchi et al. [Phys. Rev. Lett. 90, 196803 (2003)], we have theoretically investigated the electronic properties of MIGS at interfaces between various alkali halides and a metal represented by a jellium with the first-principles density functional method. We have found that, on top of the usual evanescent state, MIGS generally have a long tail on halogen sites with a pz-like character, whose penetration depth (λ) is as large as half the lattice constant of bulk alkali halides. This implies that λ, while little dependent on the carrier density in the jellium, is dominated by the lattice constant (hence by energy gap) of the alkali halide, where λLiF < λ LiCl < λLiI. We also propose a possibility of the MIGS working favorably for the exciton-mediated superconductivity.

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Insulator at the Ultrathin Limit: MgO on Ag(001)

Cited by 325 publications

References 36 publications

Giant Hysteresis of Single‐Molecule Magnets Adsorbed on a Nonmagnetic Insulator

Giant Hysteresis of Single‐Molecule Magnets Adsorbed on a Nonmagnetic Insulator

Characterizing low-coordinated atoms at the periphery of MgO-supported Au islands using scanning tunneling microscopy and electronic structure calculations

Electronic properties of metal-induced gap states at insulator/metal interfaces: Dependence on the alkali halide and the possibility of excitonic mechanism of superconductivity

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