Search arXiv⌕ Search

arXiv · cond-mat/0105152

High transport critical current density above 30 K in pure Fe-clad MgB2 tape

Abstract

Fe-clad MgB2 long tapes have been fabricated using a powder-in-tube technique. An Mg + 2B mixture was used as the central conductor core and reacted in-situ to form MgB2. The tapes were sintered in pure Ar at 800 ^(o) C for 1 h at ambient pressure. SEM shows a highly dense core with a large grain size of 100 micron. The Fe clad tape shows a sharp transition with transition width of 0.2 K and Tc0 at 37.5 K. We have achieved the highest transport critical current reported so far at 1.6 times 10^(4) A/cm^2 for both 29.5 K in 1 Tesla and 33 K in null field. R-T and critical current were also measured for fields perpendicular and parallel to the tape plane. The iron cladding shielded on the core from the applied external field, with the shielding being less effective for the field in the tape plane. Fe cladding may be advantageous for some applications as it could reduce the effects of both the self-field and external fields.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

S. Soltanian, X. L. Wang, I. Kusevic, E. Babic, A. H. Li, H. K. Liu, E. W. Collings, S. X. Dou. 2001-05-07. High transport critical current density above 30 K in pure Fe-clad MgB2 tape. https://doi.org/10.1016/s0921-4534(01)00780-8

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Layer-Parity Control of the Superconducting Diode Effect in Monolayer NbSe$_2$

The superconducting diode effect is often associated with finite-momentum pairing, although model studies indicate that rectification reflects the asymmetry of the free energy about its minimum rather than the equilibrium pair momentum itself. Using a Wannier-based, self-consistent finite-$\mathbf Q$ Bogoliubov-de Gennes approach with a Fermi-surface-adaptive quadrature that converges the critical currents, we show that the layer parity and orientation of magnetic proximity select the diode response of monolayer NbSe$_2$. For in-plane exchange, the equilibrium pair momentum $\mathbf Q_{\rm eq}$ and the diode efficiency are both linear in the layer-odd exchange contrast: parallel proximity on the two Se sublayers is reciprocal, and antiparallel proximity doubles the response. An out-of-plane component separates the two observables. It leaves $\mathbf Q_{\rm eq}$ nearly unchanged but, through pair breaking, suppresses the efficiency by more than an order of magnitude and, at low temperature, reverses it. Purely out-of-plane exchange, for which $C_3$ symmetry forbids a helical term, keeps $\mathbf Q_{\rm eq}=0$ yet produces a trigonal diode effect, controlled by the layer-even exchange and larger than the in-plane one above $0.65$~meV at $0.58$~K. Magnetic layer parity thus selects between a helical and a trigonal diode channel. This trigonal channel provides a candidate intrinsic contribution to the field-free rectification reported in NbSe$_2$/CrBr$_3$. The model predicts that two-sided out-of-plane proximity cancels it when antiparallel and, at the same exchange per layer, enhances it about fourfold when parallel, in the computed range.

cond-mat.supr-con↗

Chiral superconductivity on a closed Klein bottle: a chirality wall and its Majorana seam spectrum

We study a spinless $π$-flux lattice superconductor whose normal-state momentum-space fundamental domain is a Klein bottle. Within this model, a glide lift and a hidden antiunitary symmetry independently force the Bogoliubov--de Gennes (BdG) Chern number to vanish. A diagonal pairing breaks the antiunitary obstruction exactly when its real part is nonzero; this is necessary, not sufficient, for a chiral phase. We derive explicit Pfaffians determining Chern parity and identify three analytic families of gap closings in a real-pairing section. For a chiral state on a closed real-space Klein bottle, the prescribed pairing and gluing produce a $ΔC=2$ chirality wall. A translation-invariant unfolding resolves two co-propagating Majorana branches. Their finite-size levels depend on circumference and holonomy; the near-zero pair is lifted at first order by allowed local seam perturbations. A cut-cylinder control has the same low-energy channel count, so gluing reconnects existing gapless content. We also distinguish literal gluing from deck projection: particle--hole symmetry exchanges the deck eigenblocks, precluding their interpretation as independent BdG quotient Hamiltonians. Finite odd-frequency correlations track holonomy and local splitting, while cylinder and ordinary-wall controls show that their presence is not specific to Klein gluing. The contribution is a model-specific account of pairing compatibility, closed-surface seam spectra and finite correlations. The energy cost is evaluated for a fixed pairing background; neither a protected zero mode nor a self-consistent wall solution is claimed.

cond-mat.supr-con↗

Electrically tunable superconducting dimensionality in stripe-ordered monolayer MoTe$_2$

Dimensionality governs the stability of collective quantum states, including whether Cooper pairs can establish the phase coherence required for superconductivity. In solids, however, electronic dimensionality is usually encoded in the crystal structure and is difficult to control reversibly. Here we show evidence that monolayer 1$T^{\prime}$-MoTe$_2$ develops a stripe charge-density wave that reorganizes its low-energy electronic states into quasi-one-dimensional channels. Raman spectroscopy and scanning tunneling microscopy identify the stripe order, whereas directional transport and tunneling spectroscopy reveal superconducting correlations confined to the stripe direction and insulating behavior perpendicular to it. Electrostatic doping weakens the transverse insulating response and drives the system into phase-coherent two-dimensional superconductivity. These results show that stripe charge order can reconfigure superconducting dimensionality and make it electrically tunable within a single crystalline layer.

cond-mat.supr-con↗