Exchange Biasing Single Molecule Magnets: Coupling of TbPc<sub>2</sub> to Antiferromagnetic Layers

Rizzini, A. Lodi; Krull, Cornelius; Balashov, T.; Mugarza, Aitor; Nistor, Corneliu; Yakhou, F.; Sessi, Violetta; Klyatskaya, Svetlana; Rüben, Mario; Stepanow, Sebastian; Gambardella, Pietro

doi:10.1021/nl302918d

Cited by 70 publications

(68 citation statements)

References 42 publications

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“…This was confirmed by the detection of the XAS and XMCD signals for the [(Pc)Tb(Pc)] 0 film on a CoO/MnO/Ag(100) substrate with Co spin in OP magnetic anisotropy. In addition, when the field cooled from 300 to 8 K at B = + 5T θ = 0, the Tb SMM on an antiferromagnetic metal Mn substrate produced similar XAS and XMCD spectra to those on the CoO support[100].In contrast to the closed hysteresis loop, an open but negatively shifted hysteresis of magnetization with finite remanence and a coercivity field of 44 mT was observed for [(Pc)Tb(Pc)] 0 on Mn, which demonstrated the small degree of exchange-coupling for [(Pc)Tb(Pc)] 0 with the substrate due to the pinned spins of the antiferromagnetic metal Mn substrate. A thin film of [(Pc)Tb(Pc)] 0 was deposited onto a ferromagnetic substrate comprising perovskite manganite with the formula of La 0.3 Sr 0.7 MnO 3 (LSMO), which was grown on strontium titanium oxide (STO) [101].…”

mentioning

confidence: 84%

“…A magnetic field was applied with angles of 0 and 70 with respect to the surface, which corresponded to OP and IP magnetization, respectively. After the magnetization was saturated at 5 T and the field was subsequently fixed to zero, a strong remanent XMCD intensity was observed for the Ni (OP) substrate and Tb M a n u s c r i p t [(Pc)Tb(Pc)] 0 has also been deposited onto antiferromagnetic substrates comprising insulating CoO and metallic Mn thin films over a single crystal Ag (100) surface [100], which were characterized by element-resolved X-ray absorption spectroscopy at the Co/Mn L 2,3 and Tb M 4,5 edges under an applied magnetic field, where the angle θ was 0 and 45 relative to the sample surface, respectively [100]. A very weak field-induced non-zero XMCD signal was detected for the CoO substrate, According to these experimental results, the magnetic anisotropy of multiple-decker SMM molecules on different substrate is readily influenced by the molecular arrangement, the interaction between the molecule and the substrate surface, and the nature of the deposited substrate.…”

Section: Towards Spintronic Devices: Smm Properties Of Multikis(phthamentioning

confidence: 99%

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Single-molecule magnetism of tetrapyrrole lanthanide compounds with sandwich multiple-decker structures

Wang

Bian

et al. 2016

Coordination Chemistry Reviews

183

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mentioning

confidence: 84%

Section: Towards Spintronic Devices: Smm Properties Of Multikis(phthamentioning

confidence: 99%

Single-molecule magnetism of tetrapyrrole lanthanide compounds with sandwich multiple-decker structures

Wang

Bian

et al. 2016

Coordination Chemistry Reviews

183

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“…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.…”

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confidence: 97%

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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“…Therefore, the studies represent an important advancement in the understanding of the molecular coupling at the electrode interfaces and will further promote the control of spin in molecular electronics. Moreover, the magnetic properties of [TbPc 2 ] molecules deposited onto ferromagnetic Ni layer [35] and antiferromagnetic Mn and CoO layers [36] were studied through element-resolved XMCD, leading to the observation of different magnetic phenomena.…”

Section: [Lnpc 2 ] Smms On Surfacesmentioning

confidence: 99%

Conclusion and Perspective

Tang

Zhang

2015

Lanthanide Single Molecule Magnets

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As a new type of lanthanide SMMs, the novel endohedral metallofullerene (EMF) SMMs are introduced in the first part of this chapter. Furthermore, a survey of the organization of SMMs on surfaces and molecular spintronics is provided with an emphasis focusing on the applications of double-decker phthalocyanine lanthanide SMMs in spintronics. Herein, [LnPc 2 ] SMMs were not only used to fabricate three-terminal spin transistor, but its combination with carbon-based nanostructures leaded to the successful design of supramolecular spin valve. Remarkably, the nuclear spin of Tb atom embedded in [TbPc 2 ] SMM can be read out electronically through detecting the conductance jump, indicating the great promise of lanthanide SMMs in future applications.Keywords Endohedral metallofullerene · Au surface · Molecular spintronics · Spin transistor · Spin valve · Nuclear spin Naturally, the ultimate goal of SMM research is to develop future devices for possible applications in information storage and quantum computing. Therefore, now considerable efforts in some research groups have been devoted to the anchoring and organization of SMMs on surfaces as well as the design of molecular spintronics using SMMs. In contrast to traditional magnetic nanoparticles, the magnetic molecular clusters possess a well-defined structure and behave like perfectly monodisperse nanomagnets, which allow us to design a target molecule-based device. Nevertheless, one critical problem is the poor stability against water and temperature for most reported SMMs, especially lanthanide SMMs, and thus developing new type of SMM family is still necessary to obtain feasible SMMs with structural and magnetic stability when anchoring them on surfaces. Undoubtedly, a new era of collaborative research has been starting among synthetic chemists, physicists, and theorists [1]. This chapter will be devoted to this aspect.

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Exchange Biasing Single Molecule Magnets: Coupling of TbPc₂ to Antiferromagnetic Layers

Cited by 70 publications

References 42 publications

Single-molecule magnetism of tetrapyrrole lanthanide compounds with sandwich multiple-decker structures

Single-molecule magnetism of tetrapyrrole lanthanide compounds with sandwich multiple-decker structures

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

Conclusion and Perspective

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Exchange Biasing Single Molecule Magnets: Coupling of TbPc2 to Antiferromagnetic Layers

Cited by 70 publications

References 42 publications

Single-molecule magnetism of tetrapyrrole lanthanide compounds with sandwich multiple-decker structures

Single-molecule magnetism of tetrapyrrole lanthanide compounds with sandwich multiple-decker structures

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

Conclusion and Perspective

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Exchange Biasing Single Molecule Magnets: Coupling of TbPc₂ to Antiferromagnetic Layers