Dielectric Function of YNi
                    <sub>2</sub>
                    B
                    <sub>2</sub>
                    C between 10 meV and 50 eV

Widder, K.; Berner, D.; Zibold, A.; Geserich, H. P.; Knupfer, M.; Kielwein, M.; Buchgeister, M.; Fink, J. M.

doi:10.1209/0295-5075/30/1/010

Cited by 21 publications

(30 citation statements)

References 11 publications

(2 reference statements)

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“…The plasma frequencyhω pl =4.4 eV is in accord withhω pl =4.25 eV obtained in Ref. 34. From the obtained v F 's it is concluded that ω pl is mainly related to the second weakly coupled band.…”

supporting

confidence: 88%

Upper Critical Field Peculiarities of SuperconductingYNi2B2Cand
Shulga
¹
,
Drechsler
²
,
Fuchs
³

et al. 1998
Phys. Rev. Lett.
335
34
208
0
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We present new upper critical field Hc2(T ) data in a broad temperature region 0.3K ≤ T ≤ Tc for LuNi2B2C and YNi2B2C single crystals with well characterized low impurity scattering rates.The absolute values for all T , in particular Hc2(0), and the sizeable positive curvature (PC) of Hc2(T ) at high and intermediate T are explained quantitatively within an effective two-band model. The failure of the isotropic single band approach is discussed in detail. Supported by de Haas van Alphen data, the superconductivity reveals direct insight into details of the electronic structure. The observed maximal PC near Tc gives strong evidence for clean limit type II superconductors. 74.60.Ec, 74.70.Ad, 74.72Ny The discovery [1,2] of superconductivity in transition metal borocarbides has generated large interest due to their relatively high transition temperatures T c ∼ 15 to 23 K and due to the relation between the mechanisms of superconductivity in these compounds, in cuprates, and in ordinary transition metals. Another highlight is the coexistence of magnetism and superconductivity in some of these compounds containing rare earth elements [3][4][5]. A study of the non-magnetic compounds such as LNi 2 B 2 C, with L=Lu,Y,Th,Sc [6], is a prerequisite for the understanding of their magnetic counterparts. Experimental data for LuNi 2 B 2 C [7] demonstrate beside a maximal positive curvature (PC) of H c2 (T ) near T c , observed also for YNi 2 B 2 C [8,4,9], a weak T -dependent anisotropy within the tetragonal basal plane and a Tindependent out-of-plane anisotropy of the upper critical field H c2 . Both anisotropies have been described [7] in terms of nonlocal corrections to the Ginzburg-Landau (GL) equations. In this picture the PC of H c c2 ( H to the tetragonal c-axis) is caused, almost purely, by the basal plane anisotropy. However, it should be noted that the reported anisotropy of H c2 for YNi 2 B 2 C is significantly smaller than for LuNi 2 B 2 C [7,9,10] whereas its PC is comparable or even larger. Further explanations of the unusual PC of H c2 (T ), such as quasi-2D fluctuations [11], are excluded by the underestimation of H c2 (T ) at low-T [9] and the observed weak anisotropy. The quantum critical point scenario [12] as well as the bipolaronic one [13] can be disregarded because the slope of H c2 (T ) decreases for T →0 (see Fig. 1). Local density approximation (LDA) band structure calculations [14,15] predict a nearly isotropic electronic structure with rather complicated bands near the Fermi level E F . However, in analyzing the superconductivity in terms of an isotropic single-band (ISB) Eliashberg model, the multi-band character and the anisotropic Fermi surface have been widely ignored so far.Here we present and analyze theoretically new data of H c2 (T ) in a broad interval 0.3K≤ T ≤ T c for high purity LuNi 2 B 2 C and YNi 2 B 2 C single crystals. We show that typical features of both compounds, such as H c2 (0) ∼ 8 to 10 T and the unusual PC of H c2 (T ) for T > ∼ 0.5T c , cannot in any way be explained ...

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supporting

confidence: 88%

Upper Critical Field Peculiarities of SuperconductingYNi2B2Cand
Shulga
¹
,
Drechsler
²
,
Fuchs
³

et al. 1998
Phys. Rev. Lett.
335
34
208
0
View full text Add to dashboard Cite

show abstract

“…[65][66][67] The calculated imaginary part of the optical dielectric tensor ⑀ 2 () for YNi 2 B 2 C is shown in Fig. 5 where Eʈa and Eʈc represent the electric field parallel to the crystallographic axes a and c, respectively.…”

Section: Calculated Raman Spectrum For Yni 2 B 2 Cmentioning

confidence: 99%

Raman- and infrared-active phonons in superconducting and nonsuperconducting rare-earth transition-metal borocarbides from full-potential calculations

et al. 2003

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C to establish the phonon frequencies for all Raman-and ͑IR-͒ infrared-active optical qϭ0 modes using the generalized-gradient-corrected full-potential linear augmented plane-wave method. From a series of atomic force calculations the shape of the phonon potential is established. Our calculated Raman-active phonon frequencies are found to be in very good agreement with the available Raman-scattering measurements. In the case of IR-active phonons, to our best knowledge, there are no experimental frequencies available and our theoretical study is the first report for these series. The Raman-scattering intensities for all Raman-active modes of YNi 2 B 2 C are determined allowing a detailed comparison between theoretical and experimental Raman spectra. The changes in the electronic structure introduced by the phonon modes are also analyzed. Although the calculated electronic structure of these materials has three-dimensional character we found a large anisotropy in the optical dielectric function due to the layered nature of the crystal structure.

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“…A molecular nickel carborane complex has been synthesized by inorganic chemists 8 and the inclusion of nickel in other boron rich solids is well established. Nickel is a common component in the boron carbide superconductors 9 and the reactions of nickel with boron phosphide have been investigated. [10][11] Nickelocene, Ni͑C 5 H 5 ͒ 2 , has been shown to be a suitable source compound for the deposition of nickel containing thin films.…”

Section: Introductionmentioning

confidence: 99%

Nickel doping of boron carbide grown by plasma enhanced chemical vapor deposition

Hwang

1996

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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We have nickel doped boron carbide grown by plasma enhanced chemical vapor deposition. The source gas closo-1,2-dicarbadodecaborane ͑ortho-carborane͒ was used to grow the boron carbide, while nickelocene ͓Ni͑C 5 H 5 ͒ 2 ͔ was used to introduce nickel into the growing film. The doping of nickel transformed a p-type, B 5 C material, relative to lightly doped n-type silicon, to an n-type material. Both n-n heterojunction diodes and n-p heterojunction diodes were constructed, using as substrates n-and p-type Si͑111͒, respectively. With sufficient partial pressures of nickelocene in the plasma reactor, diodes with characteristic tunnel diode behavior can be successfully fabricated.

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Dielectric Function of YNi ₂ B ₂ C between 10 meV and 50 eV

Abstract: PACS. 74.72Bk -Y-based compounds. PACS. 78.00 -Optical properties of condensed-matter spectroscopy and other interactions of PACS. 79.20Kz -Other electron-impact emission phenomena. matter with particles and radiation.

Cited by 21 publications

References 11 publications

Upper Critical Field Peculiarities of SuperconductingYNi2B2Cand
Shulga
¹
,
Drechsler
²
,
Fuchs
³

et al. 1998
Phys. Rev. Lett.
335
34
208
0
View full text Add to dashboard Cite

Upper Critical Field Peculiarities of SuperconductingYNi2B2Cand
Shulga
¹
,
Drechsler
²
,
Fuchs
³

et al. 1998
Phys. Rev. Lett.
335
34
208
0
View full text Add to dashboard Cite

Raman- and infrared-active phonons in superconducting and nonsuperconducting rare-earth transition-metal borocarbides from full-potential calculations

Nickel doping of boron carbide grown by plasma enhanced chemical vapor deposition

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Dielectric Function of YNi 2 B 2 C between 10 meV and 50 eV

Abstract: PACS. 74.72Bk -Y-based compounds. PACS. 78.00 -Optical properties of condensed-matter spectroscopy and other interactions of PACS. 79.20Kz -Other electron-impact emission phenomena. matter with particles and radiation.

Cited by 21 publications

References 11 publications

Upper Critical Field Peculiarities of SuperconductingYNi2B2CandShulga1, Drechsler2, Fuchs3 et al. 1998Phys. Rev. Lett.335342080View full textAdd to dashboardCite

Upper Critical Field Peculiarities of SuperconductingYNi2B2CandShulga1, Drechsler2, Fuchs3 et al. 1998Phys. Rev. Lett.335342080View full textAdd to dashboardCite

Raman- and infrared-active phonons in superconducting and nonsuperconducting rare-earth transition-metal borocarbides from full-potential calculations

Nickel doping of boron carbide grown by plasma enhanced chemical vapor deposition

Contact Info

Product

Resources

About

Dielectric Function of YNi ₂ B ₂ C between 10 meV and 50 eV

Upper Critical Field Peculiarities of SuperconductingYNi2B2Cand
Shulga
¹
,
Drechsler
²
,
Fuchs
³

et al. 1998
Phys. Rev. Lett.
335
34
208
0
View full text Add to dashboard Cite

Upper Critical Field Peculiarities of SuperconductingYNi2B2Cand
Shulga
¹
,
Drechsler
²
,
Fuchs
³

et al. 1998
Phys. Rev. Lett.
335
34
208
0
View full text Add to dashboard Cite