Magnetic field necessary to destroy superconductivity in Al-type Se and Te

1978 ◽  
Vol 56 (9) ◽  
pp. 1133-1135 ◽  
Author(s):  
Carlo Reale
Keyword(s):  
Magnetic Field ◽  
Critical Field ◽  
Annealing Temperature ◽  
Bulk Material ◽  
Critical Magnetic Field ◽  
Normal Phase ◽  
Zero Field ◽  
Superconducting Transition ◽  
Cyclic Annealing ◽  
Glass Substrates

This paper reports the results of a study of the critical magnetic field required to restore electrical resistance in superconducting metastable Al-type Se and Te overlays vapor-quenched, respectively, on MgO, FeO, CoO, or NiO and CaO or MnO base films quench-condensed on glass substrates. The critical field was measured at various temperatures, from the superconducting transition temperature in zero field down to 0.1 K, for overlay thicknesses ranging from 100 Å up to values at which size effects disappear. The measurements were repeated after cyclic annealing at increasing temperatures up to a limiting temperature at which the overlay breaks owing to the transformation of the A1-type modification to the less dense ordinary A8-type structure.The critical field decreases steeply, with increasing thickness, down to a constant bulk-material value, increases nearly parabolically, with decreasing temperature, up to an extrapolable absolute-zero value, and decreases irreversibly with increasing annealing temperature. The superconducting-to-normal phase transition occurs through an intermediate state, which indicates that quench-deposited A1-type Se and Te are soft superconductors.

CRITICAL FIELD AND MAGNETORESISTANCE OF SINGLE CRYSTAL TmNi2B2C

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3715-3717 ◽  
Author(s):  
D. G. NAUGLE ◽  
K. D. D. RATHNAYAKA ◽  
K. CLARK ◽  
P. C. CANFIELD
Keyword(s):  
Magnetic Field ◽  
Transition Temperature ◽  
Single Crystal ◽  
Critical Field ◽  
Superconducting Transition Temperature ◽  
Magnetic Transition ◽  
Upper Critical Field ◽  
Superconducting Transition ◽  
Large Anisotropy ◽  
The Magnetic Field

In-plane resistance as a function of magnitude and direction of the magnetic field and the temperature has been measured for TmNi2B2C from above the superconducting transition temperature at 10.7 K to below the magnetic transition TN=1.5 K. The superconducting upper critical field HC2(T) exhibits a large anisotropy and structure in the vicinity of TN. The magnetoresistance above TC is large and changes sign as the direction of the magnetic field is rotated from in-plane to parallel with the c-axis.

scholarly journals Radiation Beaming in Pulsars

1971 ◽  
Vol 46 ◽  
pp. 455-456
Author(s):  
V. Canuto
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Coming Out ◽  
Critical Magnetic Field ◽  
Zero Field ◽  
Ordinary Wave ◽  
Magnetic Field Axis ◽  
Field Lines ◽  
Star Surface ◽  
The Magnetic Field

It is usually considered that the beaming of the radiation coming out of a pulsar has to be strictly connected with the mechanism producing the radiation itself. We want to show that even when the emitting mechanism gives rise to an isotropically distributed radiation, the presence of a strong magnetic field will automatically beam the radiation preferentially along the magnetic field line rather than in any other direction. We have computed the Compton scattering and from that the opacity KH (K0 is the opacity for zero field). In Figure 1 the ratio KH/K0 is given vs. θ, the angle between the propagation vector and the magnetic field axis. Hq is a critical magnetic field numerically equal to 4.41 × 1013 G; Ne is the electron density. For the ordinary wave the opacity is reduced at θ = 0, while it is unaffected at θ = π/2 where KH → K0. Even at θ = π/4 the ratio KH/K0 is still ≃ 10−2, and a good beaming is still present. The values of the parameters are proper for a neutron star surface. It is to be noticed that the ratio KH/K0 is of the order of (ω/ωH)2 or [(kT/mc2)/(H/Hq]2. One therefore can conclude that the presence of a magnetic field itself assures the beaming of radiation along the field lines.

IMPACT OF NANO-Mo ADDITION/SUBSTITUTION ON THE PHASE FORMATION AND SUPERCONDUCTIVITY OF Mg1-xMoxB2 (x=0.0to 0.50)

2007 ◽  
Vol 21 (14) ◽  
pp. 875-883 ◽  
Author(s):  
MONIKA MUDGEL ◽  
V. P. S. AWANA ◽  
H. KISHAN ◽  
RAJEEV RAWAT ◽  
A. V. NARLIKAR ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Ambient Pressure ◽  
Upper Critical Field ◽  
Zero Field ◽  
Superconducting Transition ◽  
Irreversibility Field ◽  
Sharp Transition ◽  
Mo Content ◽  
Applied Fields

Bulk polycrystalline samples of nano- Mo doped MgB 2 were synthesized by Fe tube encapsulation at ambient pressure under argon annealing (850°C). Mo substitution takes place successfully at the Mg site in Mg 1-x Mo x B 2 only till x=0.2. For higher (x>0.2) Mo content the same did not enter the MgB 2 lattice but rather forms an isomorphic lattice in the host with decreased c but an increased a-parameter. The ρ(T) measurements showed superconducting transition temperature (T c ) of around 36 K for all the samples till x=0.3 and slightly decreased values of 35 and 34 K for x=0.4 and 0.5 samples, respectively. Resistivity under magnetic field [R(T)H] experiments showed distinct single peaks in dρ/dT for all applied fields up to 8 Tesla. The estimated upper critical field H c2 is 8 Tesla for pristine and x=0.2 samples at 15.6 and 19 K, respectively. Thus H c2 increases up to x=0.20 samples and decreases afterwards. Magnetic susceptibility measurements exhibited sharp transition to superconducting state with a sizeable diamagnetic signal at 38 K (T c ) in zero field-cooled measurements. Commendable current density (J c ) of up to 105 A/cm2 in 1–2 T (Tesla) fields at temperatures (T) of up to 10 K is seen from magnetization measurements invoking the Bean's critical state model for pristine samples. For higher fields above 2.5 Tesla the J c (H) characteristics of x=0.1 and 0.2 samples were found to be slightly superior to that for pristine samples with enhanced H irr (irreversibility field).

The Study on Surface Critical Magnetic Field of a Layered Magnetic Superconductors

2014 ◽  
Vol 979 ◽  
pp. 224-227 ◽  
Author(s):  
Sumitta Meakniti ◽  
Arpapong Changjan ◽  
Pongkaew Udomsamuthirun
Keyword(s):  
Magnetic Field ◽  
Magnetic Property ◽  
Variational Method ◽  
Critical Field ◽  
Landau Equation ◽  
Critical Magnetic Field ◽  
Ginzburg Landau ◽  
Ginzburg Landau Equation ◽  
Non Linear

In this research, we studied the surface critical magnetic field () of a layered magnetic superconductors by Ginzburg-Landau approach. After the 1st Ginzburg-Landau equation was calculated, a surface critical field was solved by variational method analytically. Our formula obtained was depended on the magnetic property of superconductor. We found that Hc3 of antiferromagnetism and paramagnetism superconductors were shown the same behaviour as non-magnetic superconductors. For diamagnetism and ferromagnetism superconductors, the higher and the lower values of critical magnetic field were found, respectively. However, the Hc3 was strongly depended on the non-linear of magnetic field intend of all kind magnetism.

Coexistence of superconductivity and spin density wave orderings in Bechgaard and Fabre salts

2002 ◽  
Vol 12 (9) ◽  
pp. 197-200
Author(s):  
C. Pasquier ◽  
P. Auban-Senzier ◽  
T. Vuletic ◽  
S. Tomic ◽  
M. Heritier ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Critical Field ◽  
Density Wave ◽  
Spin Density Wave ◽  
Upper Critical Field ◽  
Small Range ◽  
Zero Field ◽  
Pressure Independent ◽  
Two Phases

In a small range of pressure, superconductivity (SC) and Spin Density Wave (SDW) states are shown to coexist in the Bechgaard salt (TMTSF)2PF6 and the Fabre salt (TMTTF)2BF4. In (TMTSF)2PF6, a precise investigation of the (P,T) phase diagram has led us to demonstrate the coexistence of the two phases with a superconducting critical temperature which is pressure independent while the critical current at zero field is strongly depressed as the pressure is decreased. In (TMTTF)2BF4, using non-linear transport measurements, we present the signature of the presence of 1D superconducting filaments in a small range of pressure. We also investigate the compound under a magnetic field applied along the c*-axis: the upper critical field is more or less pressure independent and is about 2 Tesla (at zero temperature). We suggest that such a high critical field is compatible with the penetration of the magnetic field in the insulating regions of the compound in a similar way of Josephson vortices in layered superconductors.

The Behavior of the Critical Magnetic Field and Correlation Functions in Finite-Size Hubbard-Like Models

1997 ◽  
Vol 11 (01n02) ◽  
pp. 147-152
Author(s):  
A.N. Kocharian
Keyword(s):  
Magnetic Field ◽  
Critical Field ◽  
Finite Size ◽  
Spin Correlation ◽  
Critical Magnetic Field ◽  
Spin Liquid ◽  
Lattice Geometry ◽  
Half Filling ◽  
Spin Flips ◽  
Spin Liquid State

We present exact analytical results for a critical field and correlations functions for N site ring and arbitrary size two dimensional coupled chains in a two component Hubbard model with a strong magnetic field and exactly at half-filling. The critical field near the Nagaoka instability with one spin and two spin flips is driven by Coulomb interaction, lattice geometry, dimensionality and crucially depends on the number of atomic sites N. Unsaturated ferromagnetism, reminiscent of Nagaoka-like behavior, and spin liquid state are examined in the structure of off-diagonal spin correlation at large U.

scholarly journals MAGNETIC FIELD INDUCED GAP AND KINK BEHAVIOR OF THERMAL CONDUCTIVITY

2002 ◽  
Vol 16 (04) ◽  
pp. 107-116 ◽  
Author(s):  
E. J. FERRER ◽  
V. P. GUSYNIN ◽  
V. DE LA INCERA
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
External Magnetic Field ◽  
Critical Field ◽  
Applied Magnetic Field ◽  
Interaction Model ◽  
Critical Magnetic Field ◽  
Landau Levels

The thermal conductivity of a quasiparticle (QP) system described by a relativistic four-fermion interaction model in the presence of an external magnetic field is calculated. It is shown that, for narrow widths of quasiparticles, the thermal conductivity, as a function of the applied magnetic field, exhibits a kink behavior at a critical field B c ~ T2. The kink is due to the opening of a gap in the QP spectrum at a critical magnetic field B c and to the enhancement of the transitions between the zeroth and first Landau levels. Possible applications of the results are discussed.

Anwendung der Methode der Korrelationsfunktion auf die Berechnung der Richtungsabhängigkeit von Hc2 im kubischen Einkristall

1970 ◽  
Vol 25 (8-9) ◽  
pp. 1161-1168 ◽  
Author(s):  
Klaus-Dieter Harms
Keyword(s):  
Magnetic Field ◽  
Correlation Function ◽  
Critical Field ◽  
Upper Critical Field ◽  
Critical Magnetic Field ◽  
Higher Order ◽  
Eigenvalue Equation ◽  
Cubic Symmetry ◽  
Upper Critical Magnetic Field

Abstract The upper critical magnetic field for a monocrystalline superconductor with cubic symmetry is calculated using the Method of the Correlation Function. The symmetry of the system leads to an eigenvalue equation which is solved with perturbation-theoretic methods. The upper critical field is calculated for dirty superconductors in the lowest order for which anisotropy is present. For clean superconductors, a higher order is calculated. Some results are critically compared with those in a paper by HOHENBERG and WERTHAMER.

scholarly journals Non-conventional superconductivity in magnetic In and Sn nanoparticles

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Ma-Hsuan Ma ◽  
Erdembayalag Batsaikhan ◽  
Huang-Nan Chen ◽  
Ting-Yang Chen ◽  
Chi-Hung Lee ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Transition Temperature ◽  
Weak Field ◽  
Critical Magnetic Field ◽  
Superconducting Transition ◽  
Ni Nanoparticles ◽  
Nanoparticle Assemblies ◽  
The Core ◽  
Higher Temperature ◽  
Sn Nanoparticle

AbstractWe report on experimental evidence of non-conversional pairing in In and Sn nanoparticle assemblies. Spontaneous magnetizations are observed, through extremely weak-field magnetization and neutron-diffraction measurements, to develop when the nanoparticles enter the superconducting state. The superconducting transition temperature TC shifts to a noticeably higher temperature when an external magnetic field or magnetic Ni nanoparticles are introduced into the vicinity of the superconducting In or Sn nanoparticles. There is a critical magnetic field and a critical Ni composition that must be reached before the magnetic environment will suppress the superconductivity. The observations may be understood when assuming development of spin-parallel superconducting pairs on the surfaces and spin-antiparallel superconducting pairs in the core of the nanoparticles.

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