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Numerical methods such as the banded matrix iterative approach (BMIA) represent a major advance in the direct numerical simulation of rough surface-wave scattering. This paper considers the application of iterative methods such as the BMIA to ocean-radar scattering. It is shown that for typical microwave radar frequencies and sea-surface roughness, the BMIA is actually of limited use. A more general iterative solution based on a multigrid decomposition and the generalized conjugate residual (GCR) method, is thus developed. The multigrid approach is ideally suited to the broad-band ocean surface, as it solves the scattering problem on a sequence of grids, each corresponding to a different range of spatial frequencies or length scales. This approach is applied here to several sea scattering problems, including very low grazing angles and both horizontal and vertical polarization. Good agreement is obtained with perturbation theory in the appropriate limits and several qualitative characteristics of radar backscatter data are reproduced. Index Terms - Sea surface electromagnetic scattering.

Metastable filamentary superconductivity with Tc = 10.2 K was observed in SrPt2Ge2. This is the highest Tc reported outside the iron-based 122-layer compounds. The stable phase for this compound is a non-superconducting monoclinic LaPt2Ge2-type structure with lattice parameters a = 0.4401(4) nm, b = 0.4435(4) nm, c = 0.9764(10) nm, β = 90.5°-90°. Weak diamagnetic shielding signal indicates that superconductivity is not from the major monoclinic phase, but from the minor BaFe2As2-type body-center-tetragonal (122-bct) phase with a=0.44 nm, c=0.98 nm,β=90°. Investigation on the pseudoternary system Sr(Pd1-xPtx)2Ge2 suggests that the stable bct to monoclinic structure phase transition occurs near x = 0.15. For x<0.15 with bct phase, bulk Tc increases from 3.2 K for SrPd2Ge2 to 3.6 K for SrPd1.8Pt0.2Ge2. For x>0.15 with metastable filamentary bct phase, Tc increases from 7.5 K for x = 0.5 to 9.2 K for x = 0.7 and reaches a Tc maximum of 10.2 K for SrPt2Ge2. High Tc is due to a strong quasi-2D Pt-Ge-Pt 5dxz,yz-4p-5dxz,yz hybridization in the Pt-Ge layer with squeezed-along-c-axis PtGe4 tetrahedral crystal field and Pt-5d8 spin-orbital interaction in the metastable filamentary bct phase and is another example of multi-band (dxz/dyz/dxy) non-conventional s-wave superconductor. [ABSTRACT FROM AUTHOR]

The in-plane aligned MnAs nanowires have been grown by molecular-beam epitaxy on GaAs(001) substrates at high growth temperature (≥450 °C). A discontinuous growth with break intervals (50 s’ interval per 10 s’ growth) was employed. The obtained nanowires were identified to be mainly type-B hexagonal MnAs. The influences of growth temperature and As4/Mn flux ratio on the nanowires’ morphology were investigated. Both high growth temperature and high As4/Mn flux ratio are necessary for the growth of uniaxially aligned MnAs nanowires with high aspect ratio. The magnetic anisotropy of the nanowires and their multimodal size distributions contribute to the large coercivity and special shape of the M-H loops along the magnetic easy axis, which is [1102]MnAs∥[110]GaAs. However, the longer growth time would lead to the both azimuthal alignments of the MnAs wires and the weakening of the magnetic anisotropy. [ABSTRACT FROM AUTHOR]

The resistivity, magnetization, specific heat, shear modulus, and internal friction in the charge-ordered (CO) La[sub 0.25]Ca[sub 0.75]MnO[sub 3] were studied. The electronic conduction in the CO state was found to obey Mott's variable-range hopping model with a change in the localization length Ξ near T[sub N]. A large decrease of the magnetization was observed between the Néer temperature T[sub N] and the charge ordering transition temperature T[sub CO], which was attributed to the consequence of the orbital ordering. Drastic stiffening in shear modulus and an internal friction peak appeared just below T[sub CO], and were explained as due to the coupling between the lattice strain and the orbital degree of freedom. A small upturn of the magnetization and a small softening of the ultrasound near T[sub CA] ≈ 42 K suggest the evolution of spin canting from the matrix of long-range antiferromagnetic state. [ABSTRACT FROM AUTHOR]

Presents information on a study which analyzed the effect of partial replacement of iron by other transition metals on the spin reorientation phenomena. Measurement of magnetic properties; Discussion on the spin reorientation temperature; Temperature dependence of magnetization of the aligned neodymium[sub2] iron[sub14] boron power.

Weak ferromagnetic order with ordering temperature Tm~47 K and possible superconducting transition with Tc~37 K are observed for the ruthenium-cuprate RuCa2PrCu2O8+d with the orthorhombic distortion of the tetragonal Ca2RCu2O8+δ-type fwith Tm~136 K and Tc(max) ,65 Kg phase. Anomalous temperature dependent magnetization MmsTd in both field-cooled and zero-field-cooled modes and isothermal magnetic hysteresis Mm(Ba) below and above Tm and Tc indicates a very complicated coexistence and interplay between weak-ferromagnetic order and possible superconductivity. [ABSTRACT FROM AUTHOR]

The magnetic properties of fully oxygenated hexagonal 1-xScxMnO3 (x =0, 0.5, and 1) have been investigated by means of neutron diffraction and ac magnetization measurements. All three compounds crystallized into a hexagonal symmetry of space-group P63cm. No structural changes were observed between 10 and 300 K. Anomaly of antiferromagnetic characters was observed at ∼90, 95, and 126 K for the x=0, 0.5, and 1 compounds, respectively, in the temperature dependence of the ac magnetic susceptibility, signaling the ordering of the Mn spins. Both the ferromagnetic and antiferromagnetic components, associated with the Mn spins, were revealed in the low-temperature neutron magnetic diffraction patterns. The observed magnetic intensities are consistent with a magnetic structure that can be described by using the Kovalev Γ5 irreducible representation, where the Mn moments lie in the basal MnO2 planes and the couplings between the adjacent MnO2 planes are ferromagnetic, with a saturated moment of (μz)=3.22(3)μB and 3.15(3)μB for the x=0 and 0.5 compounds, respectively. [ABSTRACT FROM AUTHOR]

The long-range ferromagnetic order was observed only for x>=0.25 in the Ca1-xSrxRuO3 (0<=x<=1) metallic system, while short-range magnetic correlation of ferromagnetic double-exchange interaction persists for x<0.25. Temperature, field, and time dependent magnetization m(T,Ba,t) for exchange-enhanced paramagnetic Ca0.8Sr0.2RuO3 near the boundary show similar electronic-inhomogeneous, spin-glass-like behavior as in Sr-free CaRuO3. X-ray Rietveld analysis and x-ray absorption near-edge structure data indicate that weaker double-exchange coupling strength Jde in the Ca-rich regime is closely related with stronger RuO6 tilting and distortion, which results with weaker Ru 4d–O 2p hybridization, narrower bandwidth W, and stronger on-site Coulomb repulsion Udd. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A metal-insulator transition near oxygen content parameter δ ∼0.018(5) was observed for the Ce-optimal-doped (x50.15) Pr[SUB1.85]Ce[SUB0.15]CuO[SUB4=δ] (-0.003&les;δ&les;0.03) electron superconductors. Cu K-edge x-ray absorption near-edge structure reflects the 3d[SUPn] character where low-energy peak A[SUB1] reflects the 3d[SUP10] configuration of Cu(I) oxidation state and A[SUB2] peak reflects the 3d[SUB10]L (L for oxygen ligand hole) for Cu(II) state. The abrupt increase of A[SUB1] peak intensity and energy separation ΔE(A[SUB2] - A[SUB1]) near δ = 0.018 coincide with the metal-insulator transition due to the formation of a broader 3d conduction band. The basal-plane penetration depth λ[SUBab] (T) for c-axis aligned powders show a d-wave power-law behavior with a linear-T temperature dependence for the 17.5 K underdoped superconductor [d50.011(5)], while a quadratic-T[SUP2] temperature dependence was observed for the 21 K optimal-doped superconductor (δ = 20.002-0.003). The superfluid density n[SUBs] ∼ λ[SUP-2,SUBab] increases from the underdoped to the optimal-doped region. [ABSTRACT FROM AUTHOR]

The Pr L[sub 3]-edge x-ray absorption near edge structure spectra and antiferromagnetic T[sub N](Pr) data for the parent system PrBa[sub 2]Cu[sub 3]O[sub 7-y] (0≤y<1) and the oxygenated system Pr[sub 1+x]Ba[sub 2-x]CU[sub 3]O[sub 7-y] (0 ≤x≤1; -0.27≤y≤0.05) are reported. The formal Pr valence in the PrO[sub 8] cage decreases from 3.18 for PrBa[sub 2]Cu[sub 3]O[sub 6.95] [T[sub N](Pr)=18.5 K], to 3.12 for Pr[sub 1.2]Ba[sub 1.8]Cu[sub 3]O[sub 6.98] (15.5 K), 3.03 for Pr[sub l.6]Ba[sub l.4]Cu[sub 3]O[sub 7.16] (8 K), and 3.00 for Pr[sub 2]BaCu[sub 3]O[sub 7.27] [T[sub N](Pr) not observed]. The Pr valence depends both on the number of holes available in the PrO[sub 8] cage and the Pr 4f-O 2p[sub π] hybridization strength. On the other hand, anomalous T[sub N](Pr) is a direct result of exchange interaction though Pr-O-Pr hybridization. However, the relative contribution from Pr[sup IV]-Pr[sup IV]superexchange via strong Pr-O orbital hybridization and Pr[sup III]-Pr[sup III]/Pr[sup III]-Pr[sup IV] superexchange paths is unclear. [ABSTRACT FROM AUTHOR]

High oxygen pressure annealed PrBa[sub 2]Cu[sub 3]O[sub 7-y] (y∼0) cuprates were prepared in order to study the effect of oxygen stoichiometric parameter y on the unusual Pr/Cu magnetic properties and/or recently reported superconductivity. The oxygen-rich orthorhombic 123-chain phase is highly unstable under high-oxygen pressure synthesis and decomposes completely in 10 bar pressure. For a smaller 2 bar prepared sample a relatively clean phase was preserved with an oxygen parameter y=0.05, as compared with y=0.11 from a conventional 1 bar flowing oxygen method. No superconductivity can be detected for all high-oxygen pressure prepared samples. Instead, Mott-insulator behavior with anomalous high Pr ordering T[sub N](Pr)=19 K was observed for PrBa[sub 2]Cu[sub 3]O[sub 6.95]. Comparison with other Pr/Ba intersubstituted Pr[sub 1-x]Ba[sub 2-x]Cu[sub 3]O[sub 7-y] cuprates is discussed. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The tetragonal c-axis alignment of T[sub c]=23 K Pr[sub 1.85]Ce[sub 0.15]CuO[sub 3.97] superconducting powder was achieved in a 1 T alignment field with rotating powder/epoxy holder perpendicular to the alignment field. The in-plane penetration depth λ[sub ab] for this electron-doped superconductor was derived using zero-field-cooled Meissner diamagnetic data with low applied field (B[sub a]

Presents a study which examined the field dependence of magnetic transitions in magnetic superconductors. Discussion on the anisotropy of the magnetic transitions; Requirement for field-induced weak ferromagnetic transitions; Details of the experimental techniques used.

Presents a study which examined the systematic variation of anomalous praseodymium (Pr) antiferromagnetic ordering temperature for two-CuO[sub2]-layer cuprate systems. Details of the experimental techniques used; Discussion on the systematic of anomalous Pr ordering.

Presents a study which performed magnetic and crystallographic measurements on the rare-earth iron boride systems. Details on permanent magnets based on rare-earth iron and boron; Materials and methods used; Results of the powder x-ray diffraction on the systems.

Presents information on a study which examined the magnetic and crystallographic properties of pseudoternary compounds of Nd[sub2](Fe[sub1-x]Cu[subx])[sub14]B. Measurement of magnetic properties of the compounds; Experimental details; Results and discussion; Conclusions.

Presents information on a study which measured the magnetic susceptibility of CeT[sub3]B[sub2] and UT[sub3]B[sub2] compounds. Experimental details; Results and discussion; Conclusions.

Presents a study which focused on copper spin orientation in titanium(barium strontium)praseodymium copper[sub2]oxygen[sub7]. Methods; Results; Discussion.

Presents a study on anomalous perpendicular magnetoanisotropy in Mn[sub4]N films on Si(100). Description of Mn[sub4]N compound; Experimental setup; Magnetic properties of the films.

Focuses on a study which examined the magnetic ordering of praseodymium (Pr) ions in Pb[sub2]Sr[sub2]PrCu[sub3]O[sub8] using neturon diffraction and alternating current susceptibility measurements. Observations on the long-range ordering of Pr spins; Preparation of the sample; Isolation of magnetic signals.