Percolation Effects in Composites Superconductor – Ferromagnetic Half-Metal

2014 ◽  
Vol 215 ◽  
pp. 100-104
Author(s):  
Victoria V. Kononenko ◽  
V.Yu. Tarenkov ◽  
A.I. Dyachenko ◽  
V.N. Varyukhin
Keyword(s):  
Metallic Nanoparticles ◽  
Cooper Pairs ◽  
Superconducting Transition ◽  
S Wave ◽  
Half Metallic ◽  
Half Metal ◽  
Spin Polarized ◽  
Wave Symmetry ◽  
Free Transition ◽  
Activated Surface

We investigated transport characteristics of composite that consist of the superconductor MgB2 and ferromagnetic half-metallic nanoparticles La0.7Ca0.3MnO3 (LCMO). The experiments were carried out in a wide temperature range with different volume content of the magnetic impurity. It was found that over 25% of the impurity manganite breaches percolation paths of the diboride magnesium. This leads to a considerable broadening of the MgB2 superconducting transition and the formation of the network of contacts through the ferromagnetic inclusions. This result shows the possibility of the spin - activated surface realization on the superconductor - manganite boundary. It's allowing the free transition of Cooper pairs with s wave symmetry of the order parameter in a ferromagnet with 100% spin-polarized carriers.

scholarly journals Superconducting switching due to a triplet component in the Pb/Cu/Ni/Cu/Co2Cr1 −x Fe x Al y spin-valve structure

2019 ◽  
Vol 10 ◽  
pp. 1458-1463 ◽  
Author(s):  
Andrey Andreevich Kamashev ◽  
Nadir Nurgayazovich Garif’yanov ◽  
Aidar Azatovich Validov ◽  
Joachim Schumann ◽  
Vladislav Kataev ◽  
...  
Keyword(s):  
Spin Valve ◽  
Alloy Layer ◽  
Switching Effect ◽  
Superconducting Transition ◽  
Deep Minimum ◽  
Half Metallic ◽  
Spin Polarized ◽  
Valve Structure ◽  
Metallic Ferromagnet ◽  
High Degree

We report the superconducting properties of the Co2Cr1 −x Fe x Al y /Cu/Ni/Cu/Pb spin-valve structure the magnetic part of which comprises the Heusler alloy layer HA = Co2Cr1 −x Fe x Al y with a high degree of spin polarization (DSP) of the conduction band and a Ni layer of variable thickness. The separation between the superconducting transition curves measured for the parallel (α = 0°) and perpendicular (α = 90°) orientation of the magnetization of the HA and the Ni layers reaches up to 0.5 K (α is the angle between the magnetization of two ferromagnetic layers). For all studied samples the dependence of the superconducting transition temperature T c on α demonstrates a deep minimum in the vicinity of the perpendicular configuration of the magnetizations. This suggests that the observed minimum and the corresponding full switching effect of the spin valve is caused by the long-range triplet component of the superconducting condensate in the multilayer. Such a large effect can be attributed to a half-metallic nature of the HA layer, which in the orthogonal configuration efficiently draws off the spin-polarized Cooper pairs from the space between the HA and Ni layers. Our results indicate a significant potential of the concept of a superconducting spin-valve multilayer comprising a half-metallic ferromagnet, recently proposed by A. Singh et al., Phys. Rev. X 2015, 5, 021019, in achieving large values of the switching effect.

In Search for Novel Sn2Co3S2-based Half-metal Ferromagnets

2014 ◽  
Vol 69 (1) ◽  
pp. 55-61 ◽  
Author(s):  
Florian Pielnhofer ◽  
Amadeus Samuel Tragl ◽  
Jan Rothballer ◽  
Richard Weihrich
Keyword(s):  
Density Functional ◽  
Substitution Effects ◽  
The Novel ◽  
Functional Theory ◽  
Half Metallic ◽  
Half Metal ◽  
Spin Polarized ◽  
Densities Of States ◽  
Metallic Ferromagnet ◽  
The Stability

Substitution effects on magnetism of shandite-type compounds have been studied by density functional theory. The decrease of the Fermi level in the novel half-metallic ferromagnet Sn2Co3S2 to higher maxima of the density of states was modeled for substitutions on the Co site by the 3d metals Fe, Mn and Cr due to a rigid band scheme. Spin-polarized energy hyper surfaces and densities of states are calculated for Sn2Co3S2, and experimentally not yet known Sn2Fe3S2, Sn2Mn3S2 and Sn2Cr3S2 with shandite-type structure. The stability of half-metallic ferromagnetic characteristics, Slater-Pauling behavior, and alternative metastable spin states are discussed.

scholarly journals Magnetization Control and Transfer of Spin-Polarized Cooper Pairs into a Half-Metal Manganite

2017 ◽  
Vol 8 (4) ◽  
Author(s):  
A. Srivastava ◽  
L. A. B. Olde Olthof ◽  
A. Di Bernardo ◽  
S. Komori ◽  
M. Amado ◽  
...  
Keyword(s):  
Cooper Pairs ◽  
Half Metal ◽  
Spin Polarized

Non-Dirac Chern insulators with large band gaps and spin-polarized edge states

Nanoscale ◽  
2018 ◽  
Vol 10 (18) ◽  
pp. 8569-8577 ◽  
Author(s):  
Y. Xue ◽  
J. Y. Zhang ◽  
B. Zhao ◽  
X. Y. Wei ◽  
Z. Q. Yang
Keyword(s):  
Band Gap ◽  
Band Gaps ◽  
Edge States ◽  
Half Metallic ◽  
Spin Polarized ◽  
Chern Insulators

A non-Dirac Chern insulator with a large band gap (244 meV) and half-metallic edge states was realized in a PbC/MnSe heterostructure.

Half-metallic properties in Co2XSn (X = Ti, V and Cr) full-Heusler compound

2019 ◽  
Vol 34 (02) ◽  
pp. 2050028 ◽  
Author(s):  
H. Abbassa ◽  
A. Labdelli ◽  
S. Meskine ◽  
Y. Benaissa Cherif ◽  
A. Boukortt
Keyword(s):  
Magnetic Moment ◽  
Density Functional ◽  
Heusler Alloys ◽  
Electronic Band ◽  
Half Metallic ◽  
Lattice Constants ◽  
Half Metal ◽  
Wide Range ◽  
Metallic Ferromagnetism ◽  
Half Metallic Ferromagnetism

First-principles calculations based on density functional theory (DFT) confirm the half-metallic ferromagnetism in both [Formula: see text] and [Formula: see text], and the nearly half-metallic ferromagnetism in [Formula: see text] Heusler alloys with the [Formula: see text]-type structure [Formula: see text]. The electronic band structures and density of states (DOS) calculations of the [Formula: see text] and [Formula: see text] compounds show that the spin-up electrons are metallic, whereas the spin-down bands are semiconducting with a gap of 0.47 eV and 0.53 eV, respectively, with 0.21 eV and 0.36 eV as a spin-flip gap, respectively. The [Formula: see text] and [Formula: see text] Heusler were half-metal compounds with magnetic moment of [Formula: see text] and [Formula: see text] at the equilibrium lattice constants [Formula: see text] Å and [Formula: see text] Å, respectively, which agrees with the Slater–Pauling rule, and have 100% polarization for a wide range of lattice parameters. The [Formula: see text] is a nearly half-metal (NHF) compound with magnetic moment of [Formula: see text] and 92.9% polarization at the equilibrium lattice constants [Formula: see text] Å and acquire half-metal behavior under the pressure 16.70 GPa.

scholarly journals Smart meta-superconductor MgB2 constructed by the dopant phase of luminescent nanocomposite

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yongbo Li ◽  
Honggang Chen ◽  
Mingzhong Wang ◽  
Longxuan Xu ◽  
Xiaopeng Zhao
Keyword(s):  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Ex Situ ◽  
Cooper Pairs ◽  
Superconducting Transition ◽  
Luminescence Characteristic ◽  
Dopant Content ◽  
Strong Luminescence

Abstract On the basis of the idea that the injecting energy will improve the conditions for the formation of Cooper pairs, a smart meta-superconductor (SMSC) was prepared by doping luminescent nanocomposite Y2O3:Eu3+/Ag in MgB2. To improve the superconducting transition temperature (TC) of the MgB2-based superconductor, two types of Y2O3:Eu3+/Ag, which has the strong luminescence characteristic, with different sizes were prepared and marked as m-Y2O3:Eu3+/Ag and n-Y2O3:Eu3+/Ag. MgB2 SMSC was prepared through an ex situ process. Results show that when the dopant content was fixed at 2.0 wt.%, the TC of MgB2 SMSC increased initially then decreased with the increase in the Ag content in the dopant. When the Ag content is 5%, the TC of MgB2 SMSC was 37.2–38.0 K, which was similar to that of pure MgB2. Meanwhile, the TC of MgB2 SMSC doped with n-Y2O3:Eu3+/Ag increased initially then decreased basically with the increase in the content of n-Y2O3:Eu3+/Ag, in which the Ag content is fixed at 5%. The TC of MgB2 SMSC doped with 0.5 wt.% n-Y2O3:Eu3+/Ag was 37.6–38.4 K, which was 0.4 K higher than that of pure MgB2. It is thought that the doping luminescent nanocomposite into the superconductor is a new means to improve the TC of SMSC.

scholarly journals s-Wave Symmetry Along the c-Axis and s+d In-plane Superconductivity in Bulk YBa2Cu4O8

2007 ◽  
Vol 21 (2) ◽  
pp. 81-85 ◽  
Author(s):  
R. Khasanov ◽  
A. Shengelaya ◽  
J. Karpinski ◽  
A. Bussmann-Holder ◽  
H. Keller ◽  
...  
Keyword(s):  
S Wave ◽  
Wave Symmetry
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