Superconductivity of<i>B1</i>-MoN films annealed under high pressure

Ihara, Hideo; Hirabayashi, Masayuki; Senzaki, Kiyoshi; Kimura, Y.; Kezuka, Hiroshi

doi:10.1103/physrevb.32.1816

Cited by 46 publications

(22 citation statements)

References 7 publications

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“…The molybdenum nitrides present several superconducting crystalline phases: γ-Mo 2 N (cubic) with T c ~ 5 K [4], β-Mo 2 N (tetragonal) with superconducting critical temperature T c ~ 5 K [5] and δ-MoN (hexagonal) with T c ~ 13 K [6,7]. Thin films of the different crystalline structures have been sintered through chemical and physical routes [8,9,10,11,12,13]. An outstanding feature for γ-Mo 2 N and δ-MoN is that sharp superconducting transitions have been observed for epitaxial and polycrystalline thin films [14,15,16].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of nanocrystalline δ-MoN by thermal annealing of amorphous thin films grown on (100) Si by reactive sputtering at room temperature

et al. 2018

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We report on the synthesis and characterization of nanocrystalline δ-MoN by crystallization of amorphous thin films grown on (100) Si by reactive sputtering at room temperature.Films with chemical composition MoN were grown using a deposition pressure of 5mTorr with a reactive mixture of Ar/(Ar+N 2 )=0.5. The as-grown films display mostly amorphous structure. Nanocrystalline δ-MoN phase is obtained after annealing at temperatures above 600 °C. The superconducting critical temperature T c depends on film thickness. Thick films (170 nm) annealed at 700 °C for 30 min display a T c = 11.2 K (close to the one reported for bulk specimens: 13 K), which is gradually suppressed to 7.2 K for 40 nm thick δ-MoN films. Our results provide a simple method to synthesize superconducting nitride thin films on silicon wafers with T c above the ones observed for conventional superconductors such as Nb.

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Section: Introductionmentioning

confidence: 99%

Synthesis of nanocrystalline δ-MoN by thermal annealing of amorphous thin films grown on (100) Si by reactive sputtering at room temperature

et al. 2018

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“…1,2 ␥-Mo 2 N is known as a superconductor with T c ϳ 5 K. 3 We reported that ␤-Mo 2 N is also a superconductor with T c ϳ 5 K. 4 It was reported that the hexagonal ␦-MoN was crystallized in a slightly distorted NiAs type structure under 6 GPa, 5,6 and the resulting phase showed superconductivity with T c ϳ 12 K. 3,5 A theoretical study predicted that MoN with the cubic NaCl type structure ͑so called B1-MoN͒ would have T c as high as 29 K. [7][8][9][10] Since B1-MoN is believed to be a metastable phase, many studies adopted thin film deposition techniques, such as magnetron sputter, ion-beam assisted deposition, and ion implanting for the synthesis of the phase. [11][12][13][14][15][16][17] The B1-MoN films reported in the literature, however, have not exhibited such "high T c ." Later, theoretical studies predicted the elastic instability of the B1-MoN cubic structure, and suggested that orthorhombic, tetragonal or trigonal distortions would be more preferable.…”

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confidence: 99%

Structural distortion and suppression of superconductivity in stoichiometricB1−MoNepitaxial thin films

2006

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Molybdenum nitride films with the NaCl structure ͑B1-MoN͒ were epitaxially grown on ␣-Al 2 O 3 ͑001͒ and MgO͑001͒ substrates at 973 K by pulsed laser deposition ͑PLD͒ under nitrogen radical irradiation. The highly crystalline epitaxial films enabled us to determine the three-dimensional cell parameters, which was motivated by theoretical calculations that B1-MoN, a predicted superconductor, is elastically unstable against tetragonal and trigonal distortions. On ␣-Al 2 O 3 ͑001͒, the B1-MoN phase ͑composition, Mo 1 N 0.98 ͒ was grown with its ͑111͒ planes parallel to the substrate surface. X-ray diffraction analysis with a multiaxes diffractometer detected only a small trigonal lattice distortion ͓a = 0.4219͑3͒ nm, ␣ = 89.28͑5͒°͔ with an expansion along the ͓111͔ direction perpendicular to the substrate surface. The film grown on MgO͑001͒ had the MoN 1.03 composition and showed a slight tetragonal distortion ͑a = 0.4213 and c = 0.424 nm͒ due to fitting to the MgO substrate lattice ͑a = 0.4213 nm͒. These two stoichiometric films showed no superconductivity above 2 K. A lower nitrogen content ͑MoN 0.86 ͒ film was obtained on ␣-Al 2 O 3 ͑001͒ using a higher deposition rate. The corresponding film had a much smaller lattice constant ͓a = 0.4184͑3͒ nm͔, and a similar distortion ͓␣ = 89.41͑5͒°͔. The B1-MoN 0.86 film showed superconductivity with a transition temperature T c = 4.2 K. The suppression of the superconductivity of the former stoichiometric phase can be interpreted in terms of the lattice expansion.

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“…Mo and molybdenum nitride thin films have been extensively used in various technological areas, due to their remarkable properties such as high hardness, high brittleness, high melting point, high superconductivity transition temperature in several of these compounds, good chemical stability [14,15], wear and corrosion resistance [4], and catalytic properties [16].…”

Section: Introductionmentioning

confidence: 99%

The wet corrosion of Mo and Mo-Ti alloy thin film - Part IV: The effect of nitriding

Tomachuk

Mitton

Špringer

et al. 2006

Materials and Corrosion

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A considerable number of detailed investigations have been carried out on the deposition and characterisation of molybdenum and molybdenum-titanium-nitride films by employing a variety of techniques. However, very little is currently known about the effect of composition (N 2 /Ar flow rate) on the corrosion properties of MoN and MoTiN thin films for aggressive ambient conditions. In this work, the electrochemical and corrosion behaviour of MoN and MoTiN thin films, produced by Physical Vapour Deposition (PVD) with different N 2 /Ar flow rates, has been investigated by Electrochemical Impedance Spectroscopy (EIS) in aerated alkaline chloride solution and compared with the behaviour of pure molybdenum in the same environment. Results obtained indicate that increasing nitrogen content in the film leads to a beneficial effect on the corrosion resistance, but results in decreased electrical conductivity of the film that may limit their application as back contact in photovoltaic modules.

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Superconductivity ofB1-MoN films annealed under high pressure

Cited by 46 publications

References 7 publications

Synthesis of nanocrystalline δ-MoN by thermal annealing of amorphous thin films grown on (100) Si by reactive sputtering at room temperature

Synthesis of nanocrystalline δ-MoN by thermal annealing of amorphous thin films grown on (100) Si by reactive sputtering at room temperature

Structural distortion and suppression of superconductivity in stoichiometricB1−MoNepitaxial thin films

The wet corrosion of Mo and Mo-Ti alloy thin film - Part IV: The effect of nitriding

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