The unoccupied electronic structure of the semi-conducting room temperature molecular magnet V(TCNE)2

Carlegrim, Elin; Kanciurzewska, Anna; Jong, M. P. de; Tengstedt, Carl; Fahlman, Mats

doi:10.1016/j.cplett.2007.12.049

Cited by 11 publications

(11 citation statements)

References 19 publications

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“…3(a)) has its absorption onset located at 284 eV, originating from a transition to the LUMO of V(TCNE) x [9,18]. When Ni is deposited on V(TCNE) x , the absorption onset decreases in intensity.…”

Section: Ni/v(tcne) X Interfacementioning

confidence: 99%

“…Vanadium tetracyanoethylene, V(TCNE) x , x~2, is one of very few room temperature organic-based magnets [5]. It is however extremely air sensitive, but recently we have reported on a new preparation method leading to improved air stability [6], which should make device fabrication less complex.The highest occupied molecular orbital (HOMO) of V(TCNE) x is mainly localized on V(3d) and characterized by strong hybridization between V(3d) and TCNE - [7,8], while the lowest unoccupied molecular orbital (LUMO) is localized on TCNE - [9]. The coupling between V 2+ and the two TCNE -is antiferromagnetic, yielding a ferrimagnetic state and hence a net spin of 1/2 for V(TCNE) x [10].…”

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confidence: 98%

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Characterization of the Ni/V(TCNE)x interface for hybrid spintronics applications

Carlegrim

Zhan

et al. 2010

Organic Electronics

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Vanadium tetracyanoethylene, V(TCNE) x , is an organic-based magnet with properties suitable for spintronics applications, e.g. spin valves. In this paper we propose a new hybrid organic spin valve design where V(TCNE) x is used as a spin-transporting and spin-filtering layer sandwiched between two ferromagnetic (FM) metal contacts, i.e. FM/V(TCNE) x /FM.As the spin injection and detection of such a device occurs at the interfaces the quality of those are of crucial importance. Therefore, the Ni/V(TCNE) x interface has been investigated by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption spectroscopy (NEXAFS) as well as compared with XPS results from a model system, Ni/TCNE. Ni chemically interact with both the vinyl and cyano groups but there is no evidence for significant diffusion of Ni into the V(TCNE) x film. As the chemical interaction affects the spin injection and detection negatively by modifying the lowest unoccupied molecular orbital (LUMO) and destroying the magnetic ordering network at the surface, these results indicate that there is need for a buffer layer between V(TCNE) x and Ni, and in extension most likely between V(TCNE) x and any FM contact. Keywords:Organic-based molecular magnets, spintronics, interfaces, photoelectron spectroscopy, magnetic semiconductors 2 IntroductionSpintronics is an emerging technique which exploits the spin state of the electron as well as its charge state when it is used as information carrier. The field has made major impact on today's life by improving hard drive information storage. Advantages of spintronics include cheaper production, faster data processing speeds, non-volatility and lower power consumption [1]. To date the most successful spintronic device is the spin valve. The principle of such a device is to sandwich a non-magnetic or semiconducting layer between two ferromagnetic (FM) contacts which act as spin injector and spin detector, respectively.The spin injector material has fixed magnetization while the magnetization of the spin detector material can be tuned by an external magnetic field. Hence, the magnetization of a spin valve can be altered giving high or low resistance, simulating a bit, "1" or "0" [2].Organic-based magnets belong to the new field of organic spintronics [3] and offer advantages such as tunability of the properties via molecular design, conductivity ranging from semiconducting to insulating, low weight, low-temperature processing etc.[4], all of which make them interesting candidates for inclusion in e.g. spin valves. Vanadium tetracyanoethylene, V(TCNE) x , x~2, is one of very few room temperature organic-based magnets [5]. It is however extremely air sensitive, but recently we have reported on a new preparation method leading to improved air stability [6], which should make device fabrication less complex.The highest occupied molecular orbital (HOMO) of V(TCNE) x is mainly localized on V(3d) and characterized by strong hybridization between V(3d) and TCNE - [7,8], while the lowest unoccupied molecu...

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Section: Ni/v(tcne) X Interfacementioning

confidence: 99%

mentioning

confidence: 98%

Characterization of the Ni/V(TCNE)x interface for hybrid spintronics applications

Carlegrim

Zhan

et al. 2010

Organic Electronics

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“…In order to discuss the electronic effects of chlorine substitution, it is useful to first build a simple molecular orbital model of the V II -acceptor •− bonding in these systems. Carlegrim et al examined analogous V[TCNE] 2 systems by near-edge x-ray absorption fine structure and photoelectron spectroscopies [28]. Their results suggest that the π* singly occupied molecular orbital (SOMO) of the TCNE •− radical anion is very close in energy to the partially occupied t 2g orbitals (POMO) of V II in a pseudo-octahedral ligand field, which facilitates strong covalent bonding and consequent strong ferrimagnetic communication (large magnetic exchange coupling).…”

Section: Discussionmentioning

confidence: 99%

A New Family of High Tc Molecule-Based Magnetic Networks: V[x-ClnPTCE]2·yCH2Cl2 (PTCE = Phenyltricyanoethylene)

2019

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Using the structural and electronic tunability of molecules to control magnetism is a central challenge of inorganic chemistry. Herein, a ten-member family of the high-ordering temperature (Tc) molecule-based magnetic coordination networks of the form V[x-ClnPTCE]2·yCH2Cl2 (PTCE = phenyltricyanoethylene, y < 0.5) were synthesized and characterized, where x is (are) the position(s) and n is the number of chlorine substitutions on the phenyl ring. These chlorophenyltricyanoethelenes are tunable analogs of the more commonly investigated tetracyanoethylene (TCNE). Varying the number and position of chlorine substitution around the phenyl ring engendered a family of network solids with significantly different magnetic ordering temperatures ranging from 146 to 285 K. The Tcs of these ferrimagnets were rationalized with the aid of cyclic voltammetry and Density Functional Theory (DFT) calculations.

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“…The lack of solvent molecules cause increased structural order, and hence, improved magnetic characteristics. 14 However, the CVD-prepared magnets still contain reacted oxygen and, generally, also residual by-products 13,15 and degrade after only a few minutes or hours in air depending on the precursor used. 9,10 Recently, an ultrahigh vacuum ͑UHV͒ compatible CVD-based preparation method was presented, 12 enabling both preparation and characterization of completely oxygen-free V͑TCNE͒ x thin films.…”

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confidence: 99%

“…8 A main problem of V͑TCNE͒ x , however, is its extreme air sensitivity 2,[9][10][11]13 and that residual solvent molecules and/or precursor-based by-products negatively affect magnetic properties 11,14 as well as introduce electron trap states. 15 Here, we present a in situ preparation method based on physical vapor deposition ͑PVD͒ resulting in films free from residual solvent molecules and precursor-based byproducts. Our first result shows that PVD-prepared V͑TCNE͒ x films can retain their magnetic properties ͑at least͒ for several weeks in air, which is a necessary step toward development of practical applications.…”

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confidence: 99%

Air-stable organic-based semiconducting room temperature thin film magnet for spintronics applications

Carlegrim

Kanciurzewska

Nordblad

et al. 2008

Applied Physics Letters

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Herein, we report on a preparation method of vanadium tetracyanoethylene, V(TCNE)x, an organic-based semiconducting room temperature thin film magnet. Previously, this compound has been reported to be extremely air sensitive but this preparation method leads to V(TCNE)x, which can retain its magnetic ordering at least several weeks in air. The electronic structure has been studied by photoelectron spectroscopy and the magnetic properties by superconducting quantum interference device. The properties mentioned above, in combination with complete spin polarization, makes this air-stable V(TCNE)x a very promising material for spintronic devices.Original publication: Elin Carlegrim, Anna Kanciurzewska, Per Nordblad and Mats Fahlman, Air-stable organic-based semiconducting room temperature thin film magnet for spintronics applications, 2008, Applied Physics Letters, (92), 163308. http://dx.doi.org/10.1063/1.2916901. Copyright: American Institute of Physics, http://apl.aip.org/apl/top.js

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The unoccupied electronic structure of the semi-conducting room temperature molecular magnet V(TCNE)2

Cited by 11 publications

References 19 publications

Characterization of the Ni/V(TCNE)x interface for hybrid spintronics applications

Characterization of the Ni/V(TCNE)x interface for hybrid spintronics applications

A New Family of High Tc Molecule-Based Magnetic Networks: V[x-ClnPTCE]2·yCH2Cl2 (PTCE = Phenyltricyanoethylene)

Air-stable organic-based semiconducting room temperature thin film magnet for spintronics applications

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