Tuning Of Anisotropy Research Articles

Tuning of anisotropy in Bi-based high temperature superconducting thin films

• Highly anisotropic Bi-based superconducting thin films. • Development of planar defects in thin films enhance vortex pinning. • Pb substitution strengthen 2D pancake arrangement of vortices in CuO planes. • Origin of anisotropy influence the axial dependence of pinning potential. The origin of the anisotropy behavior in the thin films of Bi 1.75 Pb 0.25 Sr 2 Ca 2 Cu 3 O 10±δ grown using pulsed laser deposition technique on three single crystalline substrates was investigated using magnetotransport measurements. Based on the evolution of the activation energy deduced from the magnetotransport data, it is surmised that Pb substitution in the present system strengthens the two-dimensional pancake arrangement of the vortices in the superconducting slab, which enhances the pinning of the vortices to the defect sites. The development of these planar defects with the decrease in the dimensionality of the sample was found to be the reason for the enhanced value of the pinning potential obtained in the thin film samples compared to the bulk. The interplay of Pb-assisted cation chemistry was found to have an influence on the anisotropy behavior in these films leading to an axial dependence of the pinning potential. Film grown on SrTiO 3 substrate with an anisotropy factor of ∼ 26 and higher superconducting parameters is the most anisotropic among the series of samples investigated.

Tuning of Anisotropy by Controlling Excess Fe Concentration in Fe Te0.6Se0.4

Abstract We have grown single crystals of FeTe 0.6 Se 0.4 and Fe 0.95 Te 0.6 Se 0.4 by a conventional self-flux method. The superconducting properties were investigated by magnetization measurements. We found that the anisotropy of the superconducting state for FeTe0.6Se0.4 was clearly higher than that for Fe 0.95 Te 0.6 Se 0.4 . This indicates that the excess Fe concentration can tune the anisotropy of Fe y Te 0.6 Se 0.4 .

Tuning of anisotropy in two-electron quantum dots by spin-orbit interactions

We investigate the influence of the spin-orbit interactions (SOIs) on the electron distribution and the optical absorption of a two-electron quantum dot. It is shown that the interplay between the SOIs makes the two-electron quantum dot behave like two laterally coupled quantum dots and the anisotropic distribution can be rotated from [110] to [11®0] by reversing the direction of the perpendicular electric field and detect it through the optical absorption spectrum.

Tuning of Anisotropy in IrMn/CoFe Exchange Bias Systems

In this paper, we report an enhancement of the anisotropy constant <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">AF</sub> of IrMn/CoFe exchange bias systems with the variation of the NiCr seed layer thickness. This is related to an increase in the (111) texture of IrMn parallel to the interface. Silang100rang /NiCr (Xnm)/IrMn (7 nm)/CoFe (3 nm)/Ta (10 nm) with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> = 2, 4, 6, 10, 15, 20 nm were prepared by direct current (dc) sputtering. X-ray diffraction studies revealed a peak in the (111) texture of the IrMn parallel to the interface for the samples with a 6-nm NiCr seed layer which reduced with increasing NiCr thickness. NiCr seed layer thicknesses of 2, 4, and 20 nm had negligible (111) texture. Measurement of the grain size distribution and thermal activation measurements were used to calculate the anisotropy constant of the IrMn. This was found to increase from (0.4 plusmn 0.1) times 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> ergs/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> for the sample with a 20-nm NiCr seed layer to (4.5 plusmn 2) times10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> ergs/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> for the sample with a 6-nm NiCr seed layer. TEM studies of the seed layers showed the 6-nm NiCr layer was amorphous/nanocrystalline, and the grain size increased with NiCr thickness. This change in the morphology of the seed layer results in a lattice mismatch with the IrMn reducing the (111) texture of the IrMn and hence <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">AF</sub> . This allows tuning of the anisotropy by controlling the lattice mismatch between the seed layer and the IrMn.