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dc and ac magnetic properties of two thin-walled superconducting Nb cylinders with a rectangular cross-section are reported. Magnetization curves and the ac response were studied on as-prepared and patterned samples in magnetic fields…

According to the crystal structure of MgB$_{2}$ and band structure calculations quasi-two-dimensional (2D) boron planes are responsible for the superconductivity. We report on critical fields and resistance measurements of 30 nm thick…

Superconductivity · Physics 2009-11-07 A. S. Sidorenko , L. R. Tagirov , A. N. Rossolenko , V. V. Ryazanov , R. Tidecks

We report layer-Korringa-Kohn-Rostocker calculations for bulk and surface states as well as the corresponding angle resolved photoemission (ARPES) intensities of MgB2. Our theoretical results reproduce very well the recent ARPES data by…

Condensed Matter · Physics 2009-11-07 V. D. P. Servedio , S. -L. Drechsler , T. Mishonov

We report on measurements of the magnetic moment in superconducting MgB2 single crystals. We find \mu_0H_{c2}^c(0) = 3.2 T, \mu_0H_{c2}^{ab}(0) = 14.5 T, \gamma = 4.6, \mu_0H_c(0) = 0.28 T, and \kappa(T_c) = 4.7. The standard…

Superconductivity · Physics 2009-11-07 M. Zehetmayer , M. Eisterer , H. W. Weber , J. Jun , S. M. Kazakov , J. Karpinski , A. Wisniewski

We report the low-frequency and tunneling studies of yttrium hexaboride single crystal. Ac susceptibility at frequencies 10 - 1500 Hz has been measured in parallel to the crystal surface DC felds, H0. We found that in the DC feld H0 > Hc2…

Since the discovery of MgB2 with Tc=39K, various metal diborides of MB2 have been intensively studied to find possible conventional high-temperature superconductors. A possible 2D structure of the metal diboride has been shown to be in the…

Superconductivity · Physics 2024-12-19 Jakkapat Seeyangnok , Udomsilp Pinsook , Graeme John Ackland

We study the magnetic response of superconductors in the presence of low values of a uniform applied magnetic field. We report measurements of DC magnetization and AC magnetic susceptibility performed on niobium cylinders of different…

Superconductivity · Physics 2009-10-31 F. M. Araujo-Moreira , C. Navau , A. Sanchez

A mixture of Mg and MgO has been subjected to a shock-wave pressure of 170 kbar. The ac susceptibility measurements of the product has revealed a metastable superconductivity with Tc=30 K, characterized by glassy dynamics of the shielding…

Superconductivity · Physics 2013-03-29 N. S. Sidorov , A. V. Palnichenko , D. V. Shakhrai , V. V. Avdonin , O. M. Vyaselev , S. S. Khasanov

The electronic structure of the superconducting surface sheath in a type-II superconductor in magnetic fields $H_{c2}<H<H_{c3}$ is calculated self-consistently using the Bogoliubov-de Gennes equations. We find that the pair potential…

Condensed Matter · Physics 2009-10-22 Robert J. Troy , Alan T. Dorsey

The discovery of superconductivity at 39 K in MgB2[1] raises many issues. One of the central questions is whether this new superconductor resembles a high-temperature-cuprate superconductor or a low-temperature metallic superconductor in…

The discovery of superconductor in magnesium diboride MgB2 with high Tc (39 K) has raised some challenging issues; whether this new superconductor resembles a high temperature cuprate superconductor(HTS) or a low temperature metallic…

Superconductivity · Physics 2009-11-07 M. Xu , H. Kitazawa , Y. Takano , J. Ye , K. Nishida , H. Abe , A. Matsushita , G. Kido

Superconductors with nontrivial band structure topology represent a class of materials with unconventional and potentially useful properties. Recent years have seen much success in creating artificial hybrid structures exhibiting main…

We report on the microwave surface resistance of two polycrystalline Mg11B2 samples; one consists of pristine material, the other has been irradiated at very high neutron fluence. It has already been reported that in the strongly irradiated…

Superconductivity · Physics 2008-06-20 M. Bonura , A. Agliolo Gallitto , M. Li Vigni , C. Ferdeghini , C. Tarantini

MgB2 superconducting wires were produced by the Mg diffusion method. Scanning electron microscopy (SEM), optical microscopy, dispersive x-ray analysis (EDS) and XRD diffraction were used to study the physical structure and content of the…

Superconductivity · Physics 2009-11-10 Maya Bar-Sadan , Gregory Leitus , Shimon Reich

The discovery of superconductivity in 3$d$-transition metal compounds with strong magnetism is interesting but rare. Especially for Mn-based compounds, there exist only very limited materials that show superconductivity. Here, we report the…

Superconductivity · Physics 2025-02-17 Zhe-Ning Xiang , Ying-Jie Zhang , Qing Lu , Qing Li , Yiwen Li , Tianheng Huang , Yijie Zhu , Yongze Ye , Jian Sun , Hai-Hu Wen

ABC-stacked multilayer graphene (ABC-MLG) exhibits topological surface flat bands with a divergent density of states, leading to many-body instabilities at charge neutrality. Here, we explore electronic ordering within a mean-field approach…

Superconductivity · Physics 2023-10-20 Oladunjoye A. Awoga , Tomas Löthman , Annica M. Black-Schaffer

We report the first experimental observation of superconductivity in Cd$_3$As$_2$ thin films without application of external pressure. Surface studies suggest that the observed transport characteristics are related to the polycrystalline…

We investigated the low-temperature properties of polycrystalline HoNi_2^11B_2C by means of ac-susceptibility and neutron powder diffraction in the temperature range of 1.5 to 10 K and zero magnetic field. A sample with pronounced…

Superconductivity · Physics 2009-10-31 Armin Dertinger , Andreas Kreyssig , Clemens Ritter , Michael Loewenhaupt , Hans F. Braun

X-ray diffraction studies of fine polycrystalline samples of MgB$_2$ in the superconducting state reveal that crystals orient with their \emph{c}-axis in a plane normal to the direction of the applied magnetic field. The MgB$_2$ samples…

Superconductivity · Physics 2009-11-11 J. Li , D. Vaknin , S. L. Bud'ko , P. C. Canfield , D. Pal , M. R. Eskildsen , Z. Islam , V. G. Kogan

We present a Ginzburg-Landau theory for a two-band superconductor with emphasis on MgB$_{2}$. Experiments are proposed which lead to identification of the possible scenarios: whether both $\sigma $- and $\pi $-bands superconduct or $\sigma…

Superconductivity · Physics 2007-05-23 V. A. Ivanov , J. J. Betouras , F. M. Peeters