Synthesis and photoemission study of as-grown superconducting MgB2 thin films

Ueda, Ken–ichi; Yamamoto, Hideki; Naito, Makio

doi:10.1016/s0921-4534(02)01417-x

Cited by 15 publications

(10 citation statements)

References 15 publications

(28 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The B 1s spectrum is composed of three peaks centered at ~ 188.3 eV, ~ 190.5 eV and ~ 193.5 eV. In agreement with other XPS reports, we assign the main peak located at 188.3 eV to B in MgB 2 , and the two peaks at 193.5 eV and 190.5 eV to B 2 O 3 and other contaminants of B, respectively 11 , 48 , 50 , 51 . The B 1s spectra of all measured samples are qualitatively similar and show only a single broad peak associated with MgB 2 or Mg(B 1−x C x ) 2 .…”

Section: Discussionsupporting

confidence: 89%

High-field superconductivity in C-doped MgB2 bulk samples prepared by a rapid synthesis route

Matera

Bonura

Černý

et al. 2020

Sci Rep

View full text Add to dashboard Cite

The upper critical field sets the thermodynamic limit to superconductivity. A big gap is present between the upper-critical-field values measured in MgB2 polycrystalline bulk superconductors and those of thin films, where values as high as ~ 50 T have been achieved at 4.2 K. Filling this gap would unlock the potential of MgB2 for magnet applications. This work presents the results of an extensive experimental campaign on MgB2 bulk samples, which has been guided by a Design of Experiment. We modeled the dependence of the upper critical field on the main synthesis parameters and established a new record (~ 35 T at 4.2 K) preparing C-doped bulk samples by a non-conventional rapid-synthesis route. This value appears to be an upper boundary for the upper critical field in bulk samples. Structural disorder in films seems to act selectively on one of the two bands where superconductivity in MgB2 takes place: this enhances the upper critical field while reducing the critical temperature only by few Kelvins. On the other hand, the critical temperature in bulk samples decreases monotonically when structural disorder increases, and this imposes a limit to the maximum achievable upper critical field.

show abstract

Section: Discussionsupporting

confidence: 89%

High-field superconductivity in C-doped MgB2 bulk samples prepared by a rapid synthesis route

Matera

Bonura

Černý

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Even the surface of crystalline MgB 2 films, cleaned by nonaqueous chemical etching, contained the impurities of magnesium hydroxide and carbonate. [9] Moreover, the BE values of Mg 2p and B 1s peaks measured for crystalline MgB 2 films [9,10] do not agree with the ones determined for polycrystalline MgB 2 samples [11 -13] and other transition metal diborides. [14,15] Therefore, the question whether it is possible to obtain experimentally pure and stoichiometric MgB 2 still remains open.…”

Section: Introductionmentioning

confidence: 99%

Chemical composition of magnesium boride films obtained by CVD

Crociani

Carta

Kačiulis

et al. 2008

Surface & Interface Analysis

View full text Add to dashboard Cite

The films of magnesium boride were grown on Si(100) substrate by chemical vapor deposition, starting from the synthesis of the single-source precursor Mg(BH 4 ) 2 . The deposition time was varied to study its influence on the film composition. The chemical composition of produced samples was investigated by the XPS technique. The depth profiling of MgB x films was carried out by using Ar ion sputtering combined with cyclic XPS measurements. The contributions of different chemical species (boride and oxides) in the depth profiles were separated by peak-fitting analysis of photoelectron B 1s and Auger Mg KLL spectra. In order to determine the correct parameters of peak fitting, the reference samples of MgB 2 and MgO were studied as well. The produced samples were composed of MgB x film covered by an overlayer of magnesium and boron oxides, whose thickness was increasing with deposition time. The surface of the films was enriched with magnesium, while the volume was characterized by the B : Mg ratio exceeding 2. XPS results confirmed that the bulk decomposition of Mg(BH 4 ) 2 precursor was successful; therefore, some other phenomenon, such as Mg segregation, was responsible for the formation of MgB x films with x > 2. In addition, a prolonged deposition time resulted in a thicker surface overlayer of Mg and B oxides, but it did not change the stoichiometry of the boride film.

show abstract

“…MgB2 films used as base electrodes in the junctions were deposited by molecular beam epitaxy (MBE) technique on Al2O3 (0001) substrates. Details of how the MgB2 films were deposited and their characterizations are similar to those described in Ueda and Naito (2001), Ueda et al (2002), and Ueda and Naito (2003b). A bilayer of Pd/Nb film was deposited by RF sputtering.…”

Section: Junction Fabricationmentioning

confidence: 99%

Josephson Effect in MgB2/Pd/Nb Trilayer Josephson Junctions

Malisa

2021

Tanz. J. Sci.

View full text Add to dashboard Cite

This paper reports fabrication techniques and results of MgB2/Pd/Nb trilayer Josephson junctions. The MgB2 bottom electrode was co-evaporated by molecular beam epitaxy (MBE) technique from both magnesium and boron sources at a low substrate temperature ~ 300 °C, while the interlayer and the top niobium electrode (Pd/Nb bilayer) were deposited ex-situ using RF sputtering. The junctions exhibited and Josephson effect as well as a modulation of the critical current in a magnetic field applied in a direction normal to the junction plane. Fractional and integer Shapiro steps were observed at voltages corresponding to the frequency of the applied microwave radiation field. The products of the junctions compare well with the previously reported values. The results suggest that it should be possible to fabricate all-MgB2 and MgB2 as one of the electrodes Superconductor/Normal/Superconductor (SNS), Superconductor/Insulator/Superconductor (SIS) or even Superconductor/Ferromagnet/Superconductor (SFS) tunnel junctions with interesting characteristics and for various applications. Keywords: MgB2; all-MgB2; Josephson Tunnel junctions; trilayer devices; Niobium

show abstract

Synthesis and photoemission study of as-grown superconducting MgB2 thin films

Cited by 15 publications

References 15 publications

High-field superconductivity in C-doped MgB2 bulk samples prepared by a rapid synthesis route

High-field superconductivity in C-doped MgB2 bulk samples prepared by a rapid synthesis route

Chemical composition of magnesium boride films obtained by CVD

Josephson Effect in MgB2/Pd/Nb Trilayer Josephson Junctions

Contact Info

Product

Resources

About