Near-edge x-ray absorption studies of Na-doped tetracyanoethylene films: A model system for the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">V</mml:mi><mml:msub><mml:mrow><mml:mo>(</mml:mo><mml:mi>TCNE</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>room-temperature molecular magnet

Carlegrim, Elin; Gao, Bin; Kanciurzewska, Anna; Jong, M. P. de; Zhang, Wu; Luo, Yi; Fahlman, Mats

doi:10.1103/physrevb.77.054420

Cited by 11 publications

(7 citation statements)

References 21 publications

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“…A combination of RPE, PES, and near-edge x-ray absorption fine structure ͑NEXAFS͒ has shown that the upper valence states are V ͑3d͒ derived, exhibiting a significant hybridization between V ͑3d͒ and TCNE cyano carbons, while the lower conduction states are dominated by the ligand singly occupied molecular orbital ͑SOMO͒, with no hybridization with V-related states. 10,49 The character of the computed COs is in excellent agreement with these findings. This provides indirect support for the essential features of the structure model adopted here.…”

Section: B Electronic Structuresupporting

confidence: 78%

Density functional study of the magnetic coupling inV(TCNE)2

et al. 2009

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A simple model structure of the room-temperature magnetic semiconductor V͑TCNE͒ 2 is proposed on the basis of available experimental data. The structural, electronic, and magnetic properties are investigated using hybrid-exchange density functional theory within periodic boundary conditions. A spin-polarized ferrimagnetic ground state with a total spin of 1 B per formula unit is identified. The analysis of the corresponding electronic band structure and spin distribution reveals strong interactions between the V ions and the ͓TCNE͔ ·− radicals, identified as spin carrying units. Within a simple Ising Hamiltonian, a strong antiferromagnetic coupling between the metal and its nearest-neighbor ligands is predicted which is consistent with the observed hightemperature magnetic ordering. The computed results provide useful insight into the physical origin of the exceptional magnetic behavior of V͑TCNE͒ 2 .

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Section: B Electronic Structuresupporting

confidence: 78%

Density functional study of the magnetic coupling inV(TCNE)2

et al. 2009

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“…The position of the C(1s) main peak is at slightly higher binding energy (286.8 eV) than the corresponding peak for alkali-doped TCNE (286.5 eV). 20,21 The N(1s) core levels are broadened as compared to the N(1s) of pure TCNE, similar to the case for thin films of V(TCNE) 2 . 14,22 The binding energy of the main N(1s) peak for the Ni(TCNE) films is slightly higher than the corresponding value for alkali-doped TCNE (398.8 eV).…”

Section: Resultssupporting

confidence: 59%

“…14,22 The binding energy of the main N(1s) peak for the Ni(TCNE) films is slightly higher than the corresponding value for alkali-doped TCNE (398.8 eV). 20,21 The Ni(2p) core level spectra for the normal flux and high flux Ni(TCNE) x along with pure Ni metal film are plotted in Fig. 3.…”

Section: Resultsmentioning

confidence: 99%

Ferromagnetism above room temperature in nickel–tetracyanoethylene thin films

et al. 2009

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“…The same occurs for the N K-edge ( Fig. 3(b)), which has its absorption onset at 397 eV [18]. The V L-edge (not shown here)…”

mentioning

confidence: 73%

“…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%

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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Near-edge x-ray absorption studies of Na-doped tetracyanoethylene films: A model system for theV(TCNE)xroom-temperature molecular magnet

Abstract: Near-edge x-ray absorption studies of Na-doped tetracyanoethylene films: A model system for the V(TCNE) x room-temperature molecular magnet, 2008, Physical Review B, (77), 054420. http://dx

Cited by 11 publications

References 21 publications

Density functional study of the magnetic coupling inV(TCNE)2

Density functional study of the magnetic coupling inV(TCNE)2

Ferromagnetism above room temperature in nickel–tetracyanoethylene thin films

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

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