Ferromagnetism above room temperature in nickel–tetracyanoethylene thin films

Bhatt, Pramod; Kanciurzewska, Anna; Carlegrim, Elin; Kapilashrami, Mukes; Belova, Lyubov; Rao, K. V.; Fahlman, Mats

doi:10.1039/b900756c

Cited by 18 publications

(11 citation statements)

References 24 publications

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“…These films show magnetic ordering at room temperature, opening the door to applications in organic spintronics including all‐organic spin valves and spin‐based light emitting diodes (spin‐LEDs) . An extensive array of organic‐based analogues in the M[TCNE] x family have been explored using high vacuum/temperature CVD or physical vapor deposition (PVD), including M = Co, Ni, Cr, Fe, Nb, and Mo; however, the relatively harsh film deposition conditions and lack of room temperature magnetic ordering limit their use in spintronics devices. As a result, parallel efforts have explored replacing TCNE with other organic single electron acceptors as an alternate route to synthesizing organic magnets with tunable magnetic properties and room‐temperature magnetic ordering .…”

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confidence: 99%

Thin‐Film Deposition of an Organic Magnet Based on Vanadium Methyl Tricyanoethylenecarboxylate

Harberts

Kao

et al. 2014

Advanced Materials

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The preparation and characterization of a new thin-film organic-based magnet V[MeTCEC]x (V = vanadium; MeTCEC = methyl tricaynoethylenecarboxylate) via low-temperature chemical vapor deposition (50 °C) is reported. These thin films exhibit room-temperature magnetic ordering and semiconducting behavior, demonstrating the ability of tuning their magnetic, and potentially spintronic, functionality via chemical modification of the organic ligand.

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confidence: 99%

Thin‐Film Deposition of an Organic Magnet Based on Vanadium Methyl Tricyanoethylenecarboxylate

Harberts

Kao

et al. 2014

Advanced Materials

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“…For V(TCNE) x prepared by the PVD technique this shoulder is not present since only pure vanadium and TCNE are used in the film preparation [6]. However, an excess of metal upon PVD preparation gives a low binding energy feature, which was explained by metal binding to the vinyl bridge of TCNE [6,16]. Upon increasing Ni, a shoulder on the low binding energy side of C(1s) emerges.…”

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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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“…Room temperature (RT) magnetism (Curie temperature, T C ~ 400 K) in V(TCNE) x was the major breakthrough, which accelerated the research in the field of M(TCNE) x type of magnets [1]. We have recently fabricated oxygen and contamination free, air stable Ni(TCNE) x film using PVD technique and studied magnetism [4]. However, later, it was found that the magnetism in Ni 2 TCNE compound is due to the nano-or greatersized Ni-clusters, possibly containing Cl, C and/or H species as well, in the compound [3].…”

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confidence: 99%

Organic Thin Film Magnet of Nickel-Tetracyanoethylene

Bhatt¹,

Yusuf²,

Garg³

et al. 2011

AIP Conference Proceedings

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Hybrid organic-inorganic materials consisting of a transition metal and an organic compound, TCNE form a unique class of organic magnets denoted by M(TCNE) x (where M = transition metals, and TCNE = tetracyanoethylene). The organic thin film magnet of nickel-tetracyanoethylene, Ni(TCNE) x is deposited on sputtered clean gold substrate using the physical vapor deposition (PVD) technique under ultra high vacuum (UHV) conditions at room temperature. X-ray photoelectron spectroscopy (XPS) has been used to investigate chemical and electronic properties of Ni(TCNE) x film. XPS derived film thickness and stoichiometry are found to be 6 nm and 1: 2 ratio between Ni and TCNE resulting Ni(TCNE) 2 film, respectively. In addition, XPS results do not show any signature of the presence of pure metallic Ni or Ni-clustering in the Ni(TCNE) x film.

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Ferromagnetism above room temperature in nickel–tetracyanoethylene thin films

Cited by 18 publications

References 24 publications

Thin‐Film Deposition of an Organic Magnet Based on Vanadium Methyl Tricyanoethylenecarboxylate

Thin‐Film Deposition of an Organic Magnet Based on Vanadium Methyl Tricyanoethylenecarboxylate

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

Organic Thin Film Magnet of Nickel-Tetracyanoethylene

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