Superconducting MgB2 films via precursor postprocessing approach

Paranthaman, M.; Cantoni, Claudia; Zhai, H. Y.; Christen, Hans M.; Aytuğ, Tolga; Sathyamurthy, S.; Specht, E. D.; Thompson, James R.; Lowndes, D. H.; Kerchner, H. R.; Christen, D. K.

doi:10.1063/1.1377323

Cited by 133 publications

(93 citation statements)

References 9 publications

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“…Most reports on magnesium diboride (MgB 2 ) thin-film preparation techniques describe a process that requires postdeposition annealing to produce superconducting films. [6][7][8][9][10][11][12] However, as-grown superconducting thin films are favorable for applications utilizing, for instance, Josephson junctions. Two groups 13,14 reported as-grown superconducting MgB 2 films, however, those films showed poor crystallinity.…”

Section: Highly Crystallized As-grown Smooth and Superconducting Mgb mentioning

confidence: 99%

Highly crystallized as-grown smooth and superconducting MgB2 films by molecular-beam epitaxy

Erven

Kim

Muenzenberg

et al. 2002

Applied Physics Letters

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We have investigated the growth of superconductive thin films of magnesium diboride (MgB2) by molecular-beam epitaxy. A Si(111) substrate with a seed layer of MgO was used for the growth of these films by varying parameters such as the growth temperature, Mg:B flux ratio and deposition rate as well as the background pressure. It was found that highly crystallized films could already form at 250 °C; however, only in a narrow window of growth parameters. The highest critical temperature of 35.2 K with a sharp transition (ΔTC of 0.5 K) was observed for films grown at 300 °C. Using a capping layer of MgO proved to be highly beneficial for the preservation and the smoothness of these films. Together with the fact that MgO proved to be a good seed layer for thin films of MgB2 makes it an ideal candidate for growing all epitaxial MgB2 Josephson junctions.

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Section: Highly Crystallized As-grown Smooth and Superconducting Mgb mentioning

confidence: 99%

Highly crystallized as-grown smooth and superconducting MgB2 films by molecular-beam epitaxy

Erven

Kim

Muenzenberg

et al. 2002

Applied Physics Letters

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“…Whereas in most cases rather elaborate preparation techniques, such as PLD or CVD [3,4,15,16], were employed we will present in this paper a rather easy and simple way of fabricating MgB 2 films on alumina substrates, which resulted in excellent superconducting properties, even at 20 K and in high magnetic fields.…”

Section: Introductionmentioning

confidence: 99%

Preparation and characterization of superconducting MgB₂films on alumina

Kühberger¹,

Gritzner²,

Schöppl³

et al. 2004

Supercond. Sci. Technol.

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Polycrystalline MgB 2 films with a thickness of about 1 µm were prepared at ambient pressure. The boron layers were deposited onto single-crystalline and polycrystalline Al 2 O 3 by screen printing, by airbrush techniques or by painting, followed by a reaction with Mg vapour. Grinding, mechanical and electrolytic polishing in non-aqueous dimethyl sulfoxide significantly improved the surface smoothness of the samples. The films had transition temperatures (T c(0) ) of 35 K and irreversibility fields of up to 15 T at 5 K. Transport critical current densities of 3 × 10 8 A m −2 were measured at 20 K and 1 T for MgB 2 films on single-crystalline Al 2 O 3 , whereas 8 × 10 8 A m −2 was found for films on polycrystalline Al 2 O 3 under the same conditions. Magnetization data and magneto-optical imaging indicated instabilities (flux jumps) at 4.2 K, which disappeared at around 10 K. The critical current densities of all MgB 2 films on either single-crystalline or polycrystalline Al 2 O 3 were independent of the orientation of the film with respect to the magnetic field direction.

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“…The effect of ion milling on the surface impedance was also investigated: using an Ar + beam (0.5 KV, beam current 16 mA) a nominal 60 nm layer was removed from the surface of film #1B. The motivation for that is the observation that the procedure adopted until now for film synthesis favors the growth of Mg-rich surface layers, as reported by various authors [22,51] and confirmed also by EDX (Energy Dispersive X-ray) analysis.…”

Section: Microwave Surface Impedance: Experimental Results and Discmentioning

confidence: 99%

“…Films were obtained by appropriate postannealing of an electron-beam-evaporated B precursor (500 nm) grown directly on a r-plane Al 2 O 3 single-crystal substrate. After deposition the boron film was subsequently sandwiched between cold pressed MgB 2 pellets, along with excess Mg turnings, packed inside a crimped Ta cylinder and finally annealed at 890 °C for 20-25 min [22]. Typical X-ray diffraction θ-2θ scan shows that samples have the c-axis perpendicular to the surface, whereas the pole figure evidences a random in-plane texture.…”

Section: Samples Preparation and Characterizationmentioning

confidence: 99%

STUDY OF THE ELECTRODYNAMIC RESPONSE OF MgB₂ SINTERED PELLETS AND THIN FILMS

Andreone

Gennaro

Lamura

et al. 2002

Int. J. Mod. Phys. B

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We present a number of experimental results on the temperature dependence of the magnetic penetration depth λ and on the temperature and field dependence of the microwave surface impedance Z s =R s +iX s in both pellets and thin films of MgB2 , exhibiting critical temperatures ranging between 26 and 38 K. Accurate measurements of Z s (H,T) were performed by means of a sapphire dielectrically loaded cavity operating in the microwave region (20 GHz). The study of λ(T) was carried out employing a single coil mutual inductance technique in the MHz region. An anisotropic s-wave BCS model can account for the temperature dependence experimentally observed in the penetration depth data of the best films, confirming previous reports on the conventional nature of superconductivity in diborides. On the contrary, films having a reduced value of the critical temperature and pellets show no evidence of saturation, and the experimental results strictly follow a quadratic dependence down to the lowest temperatures. We explain this behavior with the presence of metallic Mg inclusions that may locally depress the gap. The study of the surface impedance versus temperature and field shows also that the source of microwave loss can be markedly different, depending on the structural and transport properties of the samples.

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Superconducting MgB2 films via precursor postprocessing approach

Cited by 133 publications

References 9 publications

Highly crystallized as-grown smooth and superconducting MgB2 films by molecular-beam epitaxy

Highly crystallized as-grown smooth and superconducting MgB2 films by molecular-beam epitaxy

Preparation and characterization of superconducting MgB₂films on alumina

STUDY OF THE ELECTRODYNAMIC RESPONSE OF MgB₂ SINTERED PELLETS AND THIN FILMS

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Superconducting MgB2 films via precursor postprocessing approach

Cited by 133 publications

References 9 publications

Highly crystallized as-grown smooth and superconducting MgB2 films by molecular-beam epitaxy

Highly crystallized as-grown smooth and superconducting MgB2 films by molecular-beam epitaxy

Preparation and characterization of superconducting MgB2films on alumina

STUDY OF THE ELECTRODYNAMIC RESPONSE OF MgB2 SINTERED PELLETS AND THIN FILMS

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Preparation and characterization of superconducting MgB₂films on alumina

STUDY OF THE ELECTRODYNAMIC RESPONSE OF MgB₂ SINTERED PELLETS AND THIN FILMS