bluuebunny/crossref_metadata_2025 huggingface dataset:
Series capacitors and the inverse sum rule
Authors: Carlson G. T. , Illman B. L.
Published: October 2002

An exact solution for the capacitance of a three plate system is obtained and is used to quantify the error made by the inverse sum rule. Three finite, parallel disks are arranged as two capacitors in series. By treating the system as an electrostatic boundary value problem, exact solutions for the potential and capacitance are derived for the total system and for each pair of plates. The inverse sum rule is then applied to the two constituent capacitors and compared to the exact solution for the total system. Also provided are analyses of the equal plate charge hypothesis typically assumed for series capacitors, relations for the coefficients of capacitance for the system, a capacitive maximum, repulsive plate forces, charge migration on the inner plate, and plots of the field lines for the three plate system.
Quantitative classification of a historic northern Wisconsin (U.S.A.) landscape: mapping forests at regional scales
Authors: Schulte Lisa A , Mladenoff David J , Nordheim Erik V
Published: October 2002

We developed a quantitative and replicable classification system to improve understanding of historical composition and structure within northern Wisconsin's forests. The classification system was based on statistical cluster analysis and two forest metrics, relative dominance (% basal area) and relative importance (mean of relative dominance and relative density), as computed from the original U.S. Public Land Survey (PLS) bearing-tree data. Broad forest patterns are consistent between the two metrics; yet, detailed inspection highlights different aspects of historical structure. Maps produced characterize vegetation at regional scales and reveal patterns that can be interpreted in the context of environmental constraints. Our classifications have a fairly coarse spatial grain (2.6 km2) and fine-scale, patchily distributed ecosystems types are not represented. This resolution, however, is consistent with that of the PLS bearing-tree data, and maintaining it allowed retention of other beneficial map qualities, including quantitative representation of the data, replicability, flexibility, and an assessment of robustness and confidence. Our classifications are broadly applicable for regional-scale scientific and forest-management uses, including (i) assessing natural variability, (ii) determining the potential distribution of species, (iii) setting goals for ecological restoration, and (iv) calculating landscape change.
Contrasting modes of survival by jack and pitch pine at a common range limit
Authors: Greenwood Michael S , Livingston William H , Day Michael E , Kenaley Shawn C , White Alan S , Brissette John C
Published: October 2002

Freezing tolerance, reproductive development, and seed germination of jack pine (Pinus banksiana Lamb.) and pitch pine (Pinus rigida Mill.) were compared in a small sympatric population in Acadia National Park in Maine, at the southern range limit of the former and the northern limit of the latter. Freezing tolerances of vegetative shoots and roots were similar for both species. Both species flower prolifically, and there was no evidence of differences in either pollen viability, cone survival, or proportion of viable seed (6570% of the total). Regeneration success (established seedlings ranging from 1 to 13 years old) was similar overall for both species, but success by species varied greatly in some years. Jack pine regeneration was significantly associated with thinner soils, while pitch pine regeneration was associated with thicker soils in hollows. Jack pine seed germinated significantly faster than pitch pine seed, especially when daynight temperature was reduced. Pitch pine seedlings always exhibited a significantly higher shoot/root ratio than those of jack pine. The most northerly provenances of jack pine germinated significantly faster than those from the most southerly provenances. Jack pine also germinated at a significantly higher percentage than pitch pine in exposed granite sand. Thus relatively cool, dry conditions may favor establishment of jack pine seedlings, while pitch pine establishment may be favored in warmer, wetter conditions.
QUANTUM HALL LIQUID CRYSTALS
Authors: FOGLER M. M.
Published: October 2002

The stripe phase of a two-dimensional electron system in a weak magnetic field bears a close analogy to liquid crystals. However, reduced dimensionality and unusual dynamics give rise to important differences. At finite temperature they cause divergent fluctuations and nonperturbative renormalization of hydrodynamic parameters. Such effects can be verified in microwave experiments. At low temperatures the physics is dominated by quantum fluctuations. When they are large, the transition to a novel quantum nematic phase may occur, driven by quantum proliferation of dislocations. It will be signaled by an additional low-frequency resonance in the microwave response.
ZERO-BIAS CONDUCTANCE ANOMALY IN BILAYER QUANTUM HALL SYSTEMS
Authors: JOGLEKAR Y. N. , MACDONALD A. H.
Published: October 2002

Bilayer quantum Hall system at total filling factor ν=1 shows a rich variety of broken symmetry ground states because of the competition between the interlayer and intralayer Coulomb interactions. When the layers are sufficiently close, a bilayer system develops spontaneous interlayer phase-coherence that manifests itself through a spectacular enhancement of the zero-bias interlayer tunneling conductance. We present a theory of this tunneling conductance anomaly, and show that the zero-bias conductance is proportional to the square of the quasiparticle tunneling amplitude.
CURRENT-DRIVEN MAGNONS IN MAGNETIC MULTILAYERS
Authors: TSOI M.
Published: October 2002

Spin waves, or magnons, are intrinsic excitations in magnetic materials and have attracted considerable attention since introduced by Bloch in 1930.1 Recently ideas of spintronics have impacted this field dramatically. Berger2 and Sloczewski3 introduced completely new aspects of the physics of metallic ferromagnets in the presence of an electric current of high density. Excitation of magnons by an electric current has been predicted and seen in magnetic multilayers,4-6 where the driving force for the excitations is the spin-momentum transfer associated with an electric current flow. We have developed a microcontact technique (magnetic microcontact spectroscopy) to investigate the current-driven magnon generation.4,5 In our experiments we inject current densities as high as 109 A/cm2 into a Co/Cu multi-layer through a point contact made using a sharpened Ag wire carefully brought into contact with a multi-layer file. We observe current-driven magnons in multi-layers with both ferromagnetic4,5 and antiferromagnetic7 configuration of the adjacent layer magnetizations.

Some further interesting applications of the technique, particularly, for studying fluctuation phenomena, resonant magnon generation, acoustic wave generation, etc., will be presented.
TWO-COMPONENT SUPERCONDUCTIVITY OF HEAVY FERMIONIC MATERIAL UPt3
Authors: MINEEV V. P. , CHAMPEL T.
Published: October 2002

The theory of the Abrikosov lattice structures in the unconventional superconductor UPt3 under magnetic field parallel to the hexagonal crystal axis is presented. Only the two-component E2 superconducting state among the other states of different symmetry is proved to be compatible with the recent observations1 of the flux lattice in the A phase misaligned with crystallographic directions. Unlike to the one-dimensional superconductivity where anisotropic interactions caused by non-local electrodynamic corrections are essential for the vortex ordering the formation of slightly distorted triangular flux lattice in UPt3 due to the two-dimensional nature of its superconducting state can be described already in local electrodynamics.2
CeMIn5(M=Co, Ir, Rh) HEAVY FERMION SUPERCONDUCTORS AND THE UTILITY OF HIGH MAGNETIC FIELDS
Authors: SARRAO J. L.
Published: October 2002

We review the properties of the recently discovered CeMIn 5 (M=Co, Ir, Rh) heavy fermion superconductors and discuss the present state of our understanding of these materials. A particular focus is the role that magnetic fields have played in elucidating the properties of these materials. Specifically, we discuss quantum oscillation measurements on CeMIn , the influence of applied field on the linear coefficient of specific heat, γ, and the nature of the HT phase diagrams in both the normal and superconducting states of these materials.
HIGH-FIELD MAGNETIZATION, LONGITUDINAL AND TRANSVERSE MAGNETORESISTANCE OF UIrGe
Authors: CHANG S. , NAKOTTE H. , ALSMADI A. M. , LACERDA A. H. , JUNG M. H. , MIHALIK M. , PROKEŠ K. , KLAASSE J. C. P. , BRÜCK E. , DE BOER F. R.
Published: October 2002

UIrGe crystallizes in the orthorhombic TiNiSi structure and undergoes an antiferromagnetic transition around 14.1 K. The low-temperature longitudinal magnetoresistance (I // B) exhibits a pronounced field-induced step at about 13 T (14 T) and a much weaker step at about 17 T (out of field range) for B // b axis (c axis). No transition was seen for B // a. Here, we report on the magnetization results in fields up to 38 T applied along the principle directions. In addition, we present new magnetoresistance results taken in the transverse (I ⊥ B)configuration in fields up to 18 T applied along the c axis. The data show intriguing differences in comparison to those taken in the longitudinal configuration. The results are discussed in terms of field-induced magnetic transitions and/or Fermi-surface changes.
dHvA MEASUREMENTS ON La1-xCexMIn5 WHERE M=Rh, Ir AND Co
Authors: GOODRICH R. G. , ALVER U. , HARRISON N. , SARRAO J. L. , HALL D. , FISK Z.
Published: October 2002

Measurements of the de Haas-van Alphen effect in Ce x La 1-x MIn 5 show that x dependence for the three different value of M behaves quite differently. The Ce 4f electrons remain localized and have little interaction for all x in the Rh alloys, but strongly interact with the conduction electrons in both the Ir and Co alloys. Both the dependence on x of the observed frequencies and the effective masses are presented. Preliminary measurements on CeRh 1-x Ir x In 5 will also be given.
"HIGH-TEMPERATURE" OSCILLATIONS OF BISMUTH CONDUCTIVITY IN THE ULTRA-QUANTUM LIMIT
Authors: KRASOVITSKY V. B.
Published: October 2002

The special quantum oscillations of the kinetic coefficients in magnetic field ("high-temperature" oscillations - HTO) discovered by the author in 1974 have been considered. The oscillations are periodic in the reciprocal magnetic field and are characterized by a frequency higher then that of Shubnikov-de Haas (SdH) oscillations. The results of joint studies of SdH oscillations and HTO of the magnetoresistance for pure Bi and alloy BiSb in magnetic field up to 33 T are presented. The oscillations are measured for different magnetic field directions at temperature 4 – 30 K. It was found that SdH holes oscillations and holes HTO reached its quantum limit at the same value of magnetic field. The analysis of the experimental data verified one of two alternative models of HTO.
HIGH-MAGNETIC-FIELD TESTS FOR REDUCED DIMENSIONALITY IN ORGANIC SUPERCONDUCTORS: JUST HOW VALID ARE THE MOTT-IOFFE-REGEL AND ANDERSON CRITERIA?
Authors: SINGLETON J. , GODDARD P. A. , ARDAVAN A. , HARRISON N. , BLUNDELL S. J. , SCHLUETER J. A. , KINI A. M.
Published: October 2002

The interlayer transfer integrals of various organic superconductors have been deduced using high-magnetic-field techniques. The measurements demonstrate the inappropriateness of criteria used to denote incoherent interlayer transport.
MAGNETIC PHASE DIAGRAM IN FIELD INDUCED SUPERCONDUCTORS λ-(BETS)2FexGa1-xCl4
Authors: UJI S. , TERAKURA C. , TERASHIMA T. , YAKABE T. , IMANAKA Y. , TERAI Y. , YASUZUKA S. , TOKUMOTO M. , KOBAYASHI A. , SAKAI F. , TANAKA H. , KOBAYASHI H. , BALICAS L. , BROOKS J. S.
Published: October 2002

Electronic states have been investigated under high magnetic fields for quasi-two-dimensional organic conductors λ- (BETS) 2 Fe x Ga 1-x Cl 4 (x = 1.0, 0.47, 0.45, 0). Under magnetic field parallel to the c-axis, various electronic states appear, depending on x, field, and temperature. The global phase diagram for this alloy is presented and the evidence of the strong internal field due to the Fe moments is shown.
VISCOSITY OF HIGHLY POLARIZED VERY DILUTE 3He-4He MIXTURES
Authors: AKIMOTO H. , XIA J. S. , ADAMS E. D. , CANDELA D. , MULLIN W. J. , SULLIVAN N. S.
Published: October 2002

We present vibrating - wire viscosity measurements on a very dilute 3 He -4 He mixture (χ3 = 150 ppm ) in fields up to 14.8 T and temperatures down to 3 mK. The 3 He spin polarization is greater than 99% for the highest field and lowest temperature used. In these conditions, the s-wave scattering rate decreases due to a lack of quasiparticles with the minority spin state. This enhances all transport coefficients including the viscosity. At the lowest temperature, the hydrodynamic damping of the viscometer in a 14.8 T field was more than 10 times larger than in low fields. This indicates a many-fold increase in the mixture viscosity due to spin polarization.
ORDER/DISORDER TRANSITIONS OF ORTHO-PARA HYDROGEN MONOLAYERS AT LOW TEMPERATURES
Authors: SULLIVAN N. S. , KIM K. , KOKSHENEV V. B.
Published: October 2002

Experimental studies of the low temperature behavior of mono-layers of ortho - H 2 - para - H 2 mixtures using low temperature NMR techniques reveal an unusual phase diagram. An extension of the mean field approach is proposed to explain the qualitative features of the observed phase diagram. The competition between the highly frustrated short-range quadrupolar fields and the local crystal fields plays a key role in determining the nature of the ordered structures.
MAGNETOTRANSPORT IN CUPRATES AND RELATED COMPOUNDS IN HIGH MAGNETIC FIELDS: EVIDENCE FOR PREFORMED BIPOLARONS
Authors: ALEXANDROV A. S.
Published: October 2002

By extending the BCS theory to the strong-coupling regime with small bipolarons we explain the common origin of the anomalous upper critical field in high-Tc cuprates, in some organic superconductors, spin ladders and cubic oxides. The bipolaron theory accounts well for the normal state c-axis negative magnetoresistance in high magnetic fields,1 normal state diamagnetism,2 c-axis tunneling and Andreev reflection,3 angle-resolved photoemission,4 normal gaps and stripes5 observed in cuprates.
MAGNETIC FIELD AND IMPURITY EFFECTS IN PSEUDOGAP STATE OF CUPRATES
Authors: BALATSKY A. V.
Published: October 2002

Both impurities and magnetic field can be used as a tool to investigate the properties of superconducting state of cuprates. Recent STM tunneling experiments on impurity states in superconducting state provide a new set of results that can be compared with the expectations for d-wave pairing in cuprates. We will argue that impurities and magnetic field could be used to test the nature of the pseudogap state (PG).

i) We will present the extension of the theory of impurity on the pseudogap regime. The impurity such as Zn or Ni, will generate resonance state in PG state on very general grounds. Single vs double impurity peak will appear depending on the superconducting vs non-superconducting origin of the PG.

ii) For the particular proposal of the d- density wave PG (DDW) we found that out of plane magnetic field will induce complex, proportional to the field, id xy -wave density wave component. Physical properties of this, previously not considered, state will be discussed.
ANOMALOUS BEHAVIOR OF SPIN FLUCTUATIONS IN POLYCRYSTALLINE NdBa2Cu3O7
Authors: REYES A. P. , ABDELRAZEK M. , KUHNS P. L. , MOULTON W. G. , HALPERIN W. P. , KISHIO K.
Published: October 2002

Nuclear spin-lattice relaxation rate 1/T1 at the planar O(2,3) and bridging O(4) oxygen sites in NdBa 2 Cu 3 O 7 have been measured as a function of temperature in fields up to 42T. Data is characterized by extremely fast relaxation due to Nd. A well-defined peak is observed, indicative of spin freezing, occurring well below T c , and higher than T N , and whose physical origin is unknown. Extracted T1 data for Cu(2) shows enhanced Cu-Cu correlations in the superconducting state, suggesting a short-ranged order at lower temperatures.
TUNNELING SPECTROSCOPY OF THE ELECTRON-DOPED CUPRATE SUPERCONDUCTOR Pr2-xCexCuO4
Authors: BISWAS A. , FOURNIER P. , SMOLYANINOVA V. N. , BALCI H. , HIGGINS J. S. , BUDHANI A. R. C. , GREENE R. L.
Published: October 2002

The properties of electron(n)-doped cuprate superconductors show significant deviations from those of their hold(p)-doped counterparts. Experiments prior to 2000 suggested an s-wave pairing symmetry as opposed to d-wave pairing symmetry in hole-doped cuprates. Recent experiments have suggested that n-doped cuprates have a d-wave pairing symmetry. However tunneling spectroscopy of these materials have not revealed a zero bias conductance peak (ZBCP), which is a classic signature of d-wave symmetry. We present the first tunneling spectroscopy data on n-doped Pr 2-x Ce x CuO 4 (PCCO) using point contact junctions which show a systematic evolution of the ZBCP. This method of junction fabrication is important as it allows the barrier strength between the normal and the superconducting electrodes to be varied. We show that this is essential to observing the ZBCP. The n-doped cuprates have a low Tc (~25 K ) and Hc2 (~10 T ). The low Hc2 enables us to obtain the normal state in PCCO at low temperatures. We have used this to probe the density of states in the normal state of PCCO. We observe an anomalous gap even in the normal state.1 This normal state gap (NSG) becomes smaller on the over-doped side. We discuss the behavior of this NSG in the context of the pseudogap which has been observed in hole-doped cuprates.
SPECIFIC HEAT OF Mg11B2 IN MAGNETIC FIELDS: TWO ENERGY GAPS IN THE SUPERCONDUCTING STATE
Authors: FISHER R. A. , BOUQUET F. , PHILLIPS N. E. , HINKS D. G. , JORGENSEN J. D.
Published: October 2002

We present specific-heat measurements on Mg 11 B 2 in magnetic fields to 9 T. The anomaly at Tc is rapidly broadened and attenuated in fields, as expected for an anisotropic, randomly oriented superconductor. At low temperature there is a strongly field-dependent feature that shows the existence of a second energy gap. The Sommerfeld constant, γ, increases rapidly and non-linearly with magnetic field, which cannot be accounted for by anisotropy. It approaches γn = 2.6 mJ K -2 mol -1, the coefficient of the normal-state electron contribution, asymptotically for fields greater than 5 T. In zero magnetic field the data can be fitted with a phenomenological two-gap model, a generalization of a semi-empirical model for single-gap superconductors. Both of the gaps close at the same Tc; one is larger and one smaller than the BCS weak coupling limit, in the ratio ~ 4:1, and each accounts for ~ 50% of the normal-state electron density of states. The parameters characterizing the fit agree well with those from theory and are in approximate agreement with some spectroscopic measurements.
ANOMALOUS RE-ENTRANT SUPERCONDUCTIVITY IN Sr0.4K0.6BiO3: RECOVERY OF SUPERCONDUCTIVITY WITH ELECTRIC AND MAGNETIC FIELD
Authors: KIM D. C. , KIM J. S. , BARANOV A. N. , PARK Y. W. , PSHIRKOV J. S. , ANTIPOV E. V.
Published: October 2002

Anomalous re-entrant superconducting-normal resistive transition was observed in Sr 0.4 K 0.6 BiO 3 superconductor i.e., normal – supernormal behavior as temperature is increased. Contrary to previously reported re-entrant resistive behaviors in other compounds, the re-entrant resistivity appearing at zero magnetic field in Sr 0.4 K 0.6 BiO 3 is suppressed to zero by applying an external magnetic field (H) or increasing the electrical transport current (I): an observation of a zero resistive superconducting state induced by H or I. Comparisons of the normal-state resistivity data in different samples indicate an important role that disorder in the junction barriers between superconducting grains might play on the observed re-entrant resistivity behavior. Possible physical origins of this anomalous phenomenon are discussed.
THE INHOMOGENEOUS MAGNETIC FLUCTUATIONS IN THE SUPERCONDUCTING La2-xSrxCuO4
Authors: KUHNS P. L. , REYES A. P. , MOULTON W. G. , KUKOVITSKII E. F. , VAVILOVA E. L. , TEITEL'BAUM G. B.
Published: October 2002

The NMR and ESR analysis revealed the dynamical coexistence of superconductivity and the antiferromagnetic correlations in the entire superconductivity region of La 2-x Sr x CuO 4 with the spin stiffness enhancement near x = 0.12.
MAGNETIC TESTS TO REVEAL TRIPLET SUPERCONDUCTIVITY IN (TMTSF)2PF6 AND A POSSIBLE BREAKING OF A TIME REVERSAL SYMMETRY IN Sr2RuO4, LBCO, and YBCO
Authors: LEBED A. G.
Published: October 2002

We propose methods to reveal the existence of a two-component triplet order parameter (which is recently suggested to break a time reversal symmetry in Sr 2 RuO 4) and to test a possible two-component singlet d-wave order parameter in high- T c superconductors (which may also break the time reversal symmetry). We have also determined a spin part (i.e., d(k) = [dx(k) ≠ 0, dy(k) = 0, dz(k) = 0)] of a triplet order parameter1,2 in (TMTSF) 2 PF 6 under pressure by means of an analysis of the experimental H c2 measurements (I. J. Lee et al., Phys. Rev. Lett. 78, 3555 (1997)).
INFLUENCE OF ELECTRON IRRADIATION DEFECTS ON THE TRANSPORT PROPERTIES OF CUPRATES
Authors: RULLIER-ALBENQUE F. , TOURBOT R. , ALLOUL H.
Published: October 2002

We use electron irradiation at low temperature to introduce defects in a controlled manner in the cuprates. We have shown in YBCO 7 that the main influence on transport properties is due to stable defects in the CuO 2 plane. They are found analogous to Zn substitution on the copper planar site.1 Compared to impurity substitutions, the great advantage of electron irradiation is to allow to study the physical properties of a single sample with an increasing defect content. Tc and electrical resistivity measurements have been performed on electron irradiated single crystals of different cuprates (YBCO, Bi-2212, Hg-1223, T1-2201) for a wide range of hole dopings nh. A simple correlation between the decrease of Tc and the increase of residual resistivity ΔR2D is found, as expected for d ware superconductivity. The ratio ΔTc/ΔR2D, which is expected to be proportional to nh/m* is found to reproduce the variation of nh from the under-doped to the over-doped regime.2 This demonstrates that the hole content is the relevant parameter to describe the transport properties all over the phase diagram. For large defect contents, low T upturns of the resistivity are observed in under-doped YBCO 6.6 and over-doped T1-2201 (see Ref. [3]). In the highly over-doped T1 compound the decrease of conductivity scales as expected from weak localization theory. For YBCO 6.6 the large low T contribution to the resistivity is shown to be initially proportional to the defect content. It might therefore be associated to Kondo like spin flip scattering term. This would be consistent with the results on the magnetic properties induced by spinless defects such as Li (see Ref. [4]).
INTERPLAY BETWEEN SPIN AND CRYSTAL LATTICES IN ANTIFERROMAGNETIC YBa2Cu3O6.25
Authors: SANDU V. , CIMPOIASU E. , ALMASAN C. C. , PAULIKAS A. P. , VEAL B. W.
Published: October 2002

In-plane ρ ab and out-of-plane ρ c resistivity measurements were performed on the same antiferromagnetic YBa 2 Cu 3 O 6.25 single crystal over a wide range of temperatures T. ρ ab (T) exhibits two crossovers with decreasing T: a crossover from metallic to weak localization behavior at 175 K and a second crossover to two-dimensional chiral variable-range hopping VRH behavior at 115 K. The latter reflects the topologic excitations induced in the spin system. ρ c (T) displays an [Formula: see text] dependence at high T and a VRH type dependence below 115 K. The T derivative of ρ c (T) shows a kink at 32.65 K which we attribute to the antiferromagnetic ordering of the Cu(1) spins.
HIGH-FIELD TRANSPORT PROPERTIES OF T'-Ln2-xCexCuO4 (Ln=Nd, Pr, La)
Authors: SEKITANI T. , MIURA N. , NAITO M.
Published: October 2002

We report low-temperature magnetotransport in the normal state of the electron-doped superconductors, Nd 2-x Ce x CuO 4, Pr 2-x Ce x CuO 4, and La 2-x Ce x CuO 4, by suppressing the superconductivity with high magnetic fields. The normal state ρ-T curve shows an up-turn at low temperatures, which has a log T dependence with saturation at lowest temperatures. The up-turn is gradually suppressed with increasing magnetic field, resulting in negative magnetoresistance. We discuss these findings on the basis of the Kondo scattering originating from the magnetic moments of Cu 2+ ions.
PERCOLATIVE SUPERCONDUCTIVITY IN Mg1-xB2
Authors: SHARMA P. A.
Published: October 2002

Using various synthesis techniques, we have obtained a number of interesting results regarding the magnesium diboride system. First, we have observed a maximum T c of 42 K in Mg 1-x B 2 films on crystalline boron substrates, which is significantly higher than the reported value of 39 K. Furthermore, our study of Mg-vacant Mg 1-x B 2 specimens, fabricated by using high-pressure (35 MPa) sintering, provides convincing evidence for electronic phase separation, probably induced by Mg-vacancy clustering.
VORTEX GLASS TRANSITION VERSUS IRREVERSIBILITY LINE IN SUPERCONDUCTING BKBO
Authors: SZABO P. , SAMUELY P. , KACMARCIK J. , KLEIN T. , JANSEN A. G. M. , MORELLO A. , MARCUS J.
Published: October 2002

Simultaneous magnetotransport and torque magnetization measurements have been performed on superconducting (B, Ka)BiO 3 single crystals. The measurements have been carried out at very low temperatures (0.03 k < T < 2 K) and up to high magnetic fields: (30Tesla ~ Hc2(0)). The resistivity drops below the experimental resolution for a magnetic field HR(T) which is very close to the irreversibility line deduced from torque magnetometry. Close to HR(H) the resistive transition can be well by the vortex-glass scaling formalism1 suggesting that the vortex solid melts into a liquid for H > HR. Our measurements show that the irreversibility line in (K, Ba)BiO3 is closely related to this vortex glass transition line but, surprisingly, a large reversible (i.e. liquid) phase can still be observed at very low temperatures (30 m K ).
RESISTIVITY AND PENETRATION DEPTH MEASUREMENTS OF ORGANIC SUPERCONDUCTORS IN HIGH MAGNETIC FIELDS USING A TUNNEL DIODE OSCILLATOR
Authors: AGOSTA C. C. , COFFEY T. , BAYINDIR Z. , MIHUT I. , MARTIN C. , TOKUMOTO M.
Published: October 2002

We have made measurements of resistivity and penetration depth in dc-and pulsed-magnetic fields of the organic superconductors α- (ET) 2 NH 4 Hg(SCN) 4, and κ- (ET) 2 Cu(NCS) 2 using a resonant rf circuit powered by a tunnel diode oscillator (TDO). We compare the critical fields as measured by resistivity, and the TDO. All the superconductors we have studied have anisotropic critical fields with a ratio H c2 // to H c2 ⊥ of 5-17. In κ- (ET) 2 Cu(NCS) 2 we observed an almost monotonic increase in the parallel critical fields up to 24 T at 390 mK, and a sharp cusp in the critical field as a function of angle when the sample is parallel to the magnetic field. This suggests that the superconducting layers are only Josephson-coupled and the superconductivity is two-dimensional(2D). Another salt, α- (ET) 2 NH 4 Hg(SCN) 4, shows similar cusp behavior, but this material shows evidence of extreme Pauli limiting when the field is turned parallel to the conducting layers.
TRIPLET MODES IN A QUANTUM SPIN LIQUID ACROSS THE CRITICAL FIELD
Authors: CAVADINI N. , RüEGG CH. , FURRER A. , GüDEL H. U. , KRäMER K. , MUTKA H. , WILDES A. , HABICHT K. , VORDERWISCH P.
Published: October 2002

S = 1/2 TlCuCl3 is a magnetic insulator with a singlet ground state and a finite spin gap to triplet excited states. At finite fields, the degeneracy of the triplet states is lifted according to the Zeeman interaction term. Field-induced magnetic ordering occurs in TlCuCl3 at the critical field Hc ~ 6 T , when the Zeeman interaction overcomes the spin gap at the antiferromagnetic zone center. A detailed characterization of the elementary excitations realized at H > Hc is obtained by means of inelastic neutron scattering on single crystals. The general framework of field-induced quantum criticality in a three-dimensional spin liquid is illustrated on the complete dynamic range for the first time.
DYNAMICAL PROPERTIES OF FIELD-INDUCED ORDERED-STATES IN S = 1/2 ONE-DIMENSIONAL QUANTUM SPIN SYSTEMS
Authors: HAGA N. , SUGA S.-I.
Published: October 2002

We calculate the dynamical structure factors of the magnetization-plateau state in the S = 1/2 bond-alternating spin chain with a next-nearest-neighbor interaction. The results show characteristic behaviors depending on the next-nearest-neighbor interaction and the bond-alternation. We discuss the lower excited states in comparison with the exact excitation spectrums of an effective Hamiltonian.
DYNAMICAL STRUCTURE FACTORS OF THE S = 1/2 SPIN LADDER SYSTEMS WITH A DIAGONAL INTERACTION IN THE MAGNETIZATION-PLATEAU STATE
Authors: HAGA N. , SUGA S.
Published: October 2002

We investigate the dynamical structure factors of the S = 1/2 spin ladder systems with a diagonal interaction in the magnetization-plateau state. The results show characteristic behaviors depending on the chain interaction α, the ladder interaction 1 + δ and the diagonal interaction 1 - δ. The large weights are located at q = π, when δ is small. With increasing δ, the wavenumber of the large weights shifts towards q = π/2 taking the incommensurate value. The almost dispersionless behavior comes out at several combinations of α and δ, indicating that the elementary excitation is localized spatially. We discuss our results in comparison with the exact excitation spectrums of the S = 1/2 XXZ model which is an effective Hamiltonian of the present system in α ~ 0 and δ ~ 1.

Dynamical structure factors of some S = 1/2 one-dimensional quantum spin systems in the magnetic fields were measured by inelastic neutron-scattering experiments1,2 and it has been shown the theoretical results from the numerical diagonalization of finite systems can explain them.3–5
D-STRAIN, g-STRAIN, AND DIPOLAR INTERACTIONS IN THE Fe8 AND Mn12 SINGLE MOLECULE MAGNETS: AN EPR LINESHAPE ANALYSIS
Authors: HILL S. , MACCAGNANO S. , ACHEY R. , DALAL N. , PARK K.
Published: October 2002

We report high sensitivity, high field/frequency (up to 9 tesla/210 GHz) EPR measurements on the Fe8 and Mn12 single molecule magnets. Oriented single crystal studies, carried out in well defined experimental geometries, enable very accurate determinations of EPR lineshapes; we note that this is not possible when studying aligned powders or polycrystals. Analysis of individual resonances, which we can assign to known transitions, reveal complex nonlinearities in the linewidths as functions of energy eigenstate, frequency, and temperature. Our findings compare favorably with recent calculations which introduce distributions in the uniaxial anisotropy parameter D, the Landé g-factor, and dipolar interactions.
HIGH PRESSURE APPARATUS FOR TRANSPORT PROPERTIES STUDY IN HIGH MAGNETIC FIELD
Authors: HONDA F. , SECHOVSKÝ V. , MIKULINA O. , KAMARÁD J. , ALSMADI A. M. , NAKOTTE H. , LACERDA A. H.
Published: October 2002

We have designed a high pressure apparatus for measuring electrical-transport properties at low temperatures, high magnetic field and hydrostatic pressure up to 10 kbar. Details of the high-pressure cell and an exemplary study on UNiAl are described and discussed briefly.
HIGH-FIELD HALL EFFECT AND BAND STRUCTURE OF HALF-METALLIC CrO2 FILMS
Authors: WATTS S. M. , VON MOLNáR S. , JAIME M.
Published: October 2002

The Hall effect of (100)- and (110)-oriented films of the half-metallic ferromagnetic oxide CrO2, fabricated by both chemical vapor deposition and high pressure, thermal decomposition methods, has been examined in large magnetic fields up to 60 T. In all cases the Hall effect exhibits a sign reversal from positive to negative with increasing field, which we take as evidence for multi-band behavior. (110) films fabricated by both methods exhibit this sign reversal at relatively low fields. The data may be fit with a simple two-band model, which indicates the existence of highly mobile holes of p-like parentage, along with a much larger number of heavy, d-like electrons. In the (100) film the sign reversal is at much higher field. The parameters obtained from the fits allow us (with help from band structure calculations) to infer the band structure near the Fermi level and how it depends on sample strain and other structural characteristics. These details will be important for understanding carrier transport through interfaces such as for spin injection or other "spintronics" applications.
NEGATIVE MAGNETORESISTANCE IN PbTe(Mn,Cr)
Authors: KHOKHLOV D. , IVANCHIK I. , KOZHANOV A. , MOROZOV A. , SLYNKO E. , SLYNKO V. , DOBROWOLSKI W. , STORY T.
Published: October 2002

We have observed the negative magnetoresistance effect in the narrow-gap PbTe(Mn,Cr) semiconductor, in which the Fermi level is pinned within the gap nearby the conduction band edge. Previously the giant negative magentoresistance effect has been reported in PbTe(Mn,Yb), in which the Fermi level is pinned in the gap nearby the valence band edge. It is known that in the case of Yb doping the Fermi level pinning results from the 2+ - 3+ valence instability of an impurity. The same sort of the valence instability provides the Fermi level pinning in PbTe(Mn,Cr), but the conductivity is of the n-type, not of the p-type as in PbTe(Mn,Yb). Introduction of magnetic field leads to substantial drop of the PbTe(Mn,Cr) resistivity of about 30% at T = 4.2 K. This is however much lower than in PbTe(Mn,Yb), where the effect amplitude reached 3 orders of magnitude. The effect disappears at T = 15 K. Possible mechanisms of the effect are discussed.
RAMAN SCATTERING STUDY OF TEMPERATURE- AND FIELD-DEPENDENT MAGNETIC POLARON FORMATION IN (Eu,Gd)O
Authors: RHO H. , SNOW C. S. , COOPER S. L. , FISK Z. , COMMENT A. , ANSERMET J-PH.
Published: October 2002

We use Raman scattering to investigate magnetic polarons and spin-carrier interaction effects in the (Eu,Gd)O system. Raman scattering studies reveal great richness in the phase behavior of this system: a spin-fluctuation-dominated paramagnetic (PM) phase regime for T > T* > TC, a two-phase regime for T < T* in which magnetic polarons develop below T* and coexist with a remnant of the PM phase, and an inhomogeneous ferromagnetic phase regime for T < TC. We will discuss how these phase regimes evolve as functions of magnetic field, temperature, and Gd-substitution, and will compare the results with less disordered systems such as EuB6.
FEASIBILITY STUDIES FOR THE IMPLEMENTATION OF NUCLEAR MAGNETIC RESONANCE IN A 25T HYBRID MAGNET
Authors: VAN BENTUM P. J. M. , MAAN J. C. , VAN OS J. W. M. , KENTGENS A. P. M.
Published: October 2002

As an exploratory study for NMR experiments in the future 20 MW Nijmegen high field magnet laboratory, the possibilities of field stabilization and field gradient compensation in a 25 T hybrid magnet in the present installation were evaluated. High frequency field fluctuations from the power supply can be compensated to better than 10-3 ppm in the 10 Hz-10 kHz range using a computer controlled feedback system. Field mapping by 2H magnetic resonance using a homebuilt device not only showed that there are substantial axial but also strong radial field gradients. It can be shown that for any cylindrical multicoil Bitter magnet the main components of these gradients can be compensated with simple ferromagnetic inserts. In this way we achieved a linewidth under 5 ppm in 1 mm3 without further shimming or optimization. The low frequency drift of the field due to instabilities of the present power supply and the effects of temperature fluctuations of the coil are determined by simultaneous acquisition of an in-situ deuterium reference signal together with the signal of interest. This allows for a full compensation of the field fluctuations by deconvolution techniques. We will report preliminary NMR results on solid27 Al samples in fields up to 25 T.
LOCAL ORDER AND THERMAL DIFFUSIVITY IN IRON CONTAINING LIME-PHOSPHO-SILICATE GLASS-CERAMICS
Authors: SIMON S. , NEAMTU C. , ENIU D. , DADARLAT D. , SIMON V.
Published: October 2002

Thermal diffusivity, density, molar volume and electron paramagnetic resonance data on CaO-P2O5-SiO2-Fe2O3 glass-ceramics containing up to 30 mol% Fe2O3 are correlated in order to characterize the local order and thermal properties of the investigated system. The composition dependence of the thermal diffusivity at room temperature is consistent with the intermediate range order from the glass ceramics. The Fe3+-EPR data indicate that iron ions are disposed both in vitreous and crystallized phases but preponderantly in the last one.
CLASSIFICATION OF TYPES OF SOCIETAL CONFLICTS AND CHARACTERIZATION OF THEIR RESOLUTION PROCESSES BASED ON DEONTIC LOGIC
Authors: KATAI OSAMU , TODA KENTARO , KAWAKAMI HIROSHI
Published: October 2002

Focusing on the interaction among members' attitudes toward issues of common concern and members' expectance toward other members' attitudes, type classification of societal conflicts and their degree of strength are clarified. For the purpose, a vigorous theoretical framework for the examination of interrelationships among various normative concepts such as obligation, permission, prohibition, etc. is introduced, on the basis of the general theory on norms, deontic logic. By presuming several plausible laws on the way of the resolution of these conflicts and by introducing a two-dimensional representation of the conflicts with one axis representing the degree of imbalance and the other axis representing the cohesiveness of systems, a characterization method of conflict resolution processes is obtained, through which prediction and analysis of actual resolution processes can be done.
REFINEMENTS OF NASH EQUILIBRIA IN VIEW OF JEALOUS OR FRIENDLY BEHAVIOR OF PLAYERS
Authors: RUSINOWSKA AGNIESZKA
Published: October 2002

In this paper, several bargaining models, differing in some assumptions from each other, are analyzed. We consider a discrete case and a continuous case. In the former model, players bargain over a division of n objects. In the latter, parties divide one unit of infinitely divisible good. We start with an analysis of the one-round model, and then we consider a model in which players can continue to bargain. For each model, simultaneous moves as well as alternating offers of players are considered. The assumption that each player receives no more than his/her opponent proposes giving to him/her is the common assumption for all cases analyzed. Moreover, we adopt some assumptions concerning players' attitudes towards their opponents' payments, assuming that players can be either jealous or friendly. In view of the jealousy or friendliness of players, Nash equilibrium and subgame perfect equilibrium are described.
TIME-CONSISTENT SOLUTION OF A COOPERATIVE GROUP PURSUIT GAME
Authors: TARASHNINA SVETLANA
Published: October 2002

In this paper we study a time-optimal model of pursuit in which players move on a plane with bounded velocities. This game is supposed to be a nonzero-sum group pursuit game. The key point of the work is to construct and compare cooperative and non-cooperative solutions of the game and make a conclusion about the cooperation in differential pursuit games. We consider all possible cooperations between the players in the game. For this purpose with every game Γ(x0, y0, z0) we associate a corresponding game in characteristic function form Γv(x0, y0, z0). We show that in the game Γv(x0, y0, z0) there exists the core for any initial positions of the players. The core can take four various forms depending on initial positions of the players. In a dynamic game existence of the core at the initial moment of time is not sufficient for being accepted as a solution in it. We study how the core is changed when the game is proceeding and prove that the core in this game is time-consistent. Moreover, we point out an allocation from the core which could be accepted as a reasonable one by all players. Finally, we discuss advantages and disadvantages of choosing this or that allocation from the core.
On some new generalizations of Ostrowski integral inequality
Authors: Zhongxue Lü , Hongzheng Xie
Published: October 2002

Some new generalizations of Ostrowski integral inequality on
multivariate are given.
Ternary single‐source precursors for polycrystalline thin‐film solar cells
Authors: Banger Kulbinder K. , Hollingsworth Jennifer A. , Harris Jerry D. , Cowen Jonathan , Buhro William E. , Hepp Aloysius F.
Published: October 2002

The development of thin‐film solar cells on flexible, lightweight, space‐qualified substrates provides an attractive cost solution for fabricating solar arrays with high specific power (W kg−1). The use of a polycrystalline chalcopyrite absorber layer for thin‐film solar cells is considered as the next generation in photovoltaic devices. At NASA GRC we have focused on the development of new single‐source precursors (SSPs) and their utility to deposit the chalcopyrite semiconducting layer (CIS) onto flexible substrates for solar‐cell fabrication. The syntheses and thermal modulation of SSPs via molecular engineering are described. Thin‐film fabrication studies demonstrate that the SSPs can be used in a spray chemical vapor deposition process for depositing CIS at reduced temperatures, and result in electrical properties that are suitable for photovoltaic devices. Copyright © 2002 John Wiley & Sons, Ltd.
In situ syntheses of a suspension agent based on a styrene–acrylic acid copolymer for the suspension polymerization of styrene
Authors: Vilchis Leopoldo , Ríos Leonardo , Villalobos Marco A. , Guyot Alain
Published: October 2002

We carried out the suspension polymerization of styrene, initiated with benzoyl peroxide at 80°C, in the presence of the simultaneous polymerization of acrylic acid in the water phase, initiated by potassium peroxidisulfate (KPS) at the same temperature. The polymerization in the water phase was started at certain times after the beginning of the polymerization of styrene. Then, a continuous addition of KPS was carried out at a given landing rate and during variable feeding times. The water‐phase polymerization actually produced a copolymer of styrene and acrylic acid, which displayed surface‐active properties. The particle size distribution depended on the variables mentioned earlier (starting time, KPS feeding rate, and addition time), being controlled by the molecular weight, and on the composition of the copolymer produced and its availability at the increasing conversion of styrene. A second distribution of submicronic particles was produced. Both families of particles had about the same molecular weight. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3271–3285, 2002
Surface modification with waterborne fluorinated anionic polyurethane dispersions
Authors: Lim Chul Hwan , Choi Hee Sung , Noh Si Tae
Published: October 2002

Waterborne fluorinated anionic polyurethane dispersions (FAPUDs) were synthesized from tris(6‐isocyanatohexyl) isocyanurate, N‐ethyl‐N‐2‐hydroxyethyl‐perfluorooctanesulfonamide, poly(oxytetramethylene glycol) (PTMG), dimethylolpropionic acid (DMPA), hexamethylene diisocyanate, 1,4‐butanediol, and two different neutralizing agents (triethylamine and sodium carbonate). Waterborne polyurethane dispersions (PUDs) were synthesized from isophorone diisocyanate, PTMG, DMPA, and ethylenediamine as chain extenders. The particle size of the FAPUDs, based on the fluorine content and degree of neutralization (DN), was measured with dynamic light scattering. So that the surface modification and morphology variations of the PUDs through the addition of the FAPUDs could be observed, the surface energy and thermal properties of the blending films [fluorine PUD mixtures (FPMs)] were measured with contact‐angle analysis and differential scanning calorimetry. The particle size of the FAPUDs increased as the fluorine content in the FAPUDs increased and decreased as the DN increased. The surface energy of the FPM films made from the blending of the FAPUD T series (neutralization with triethylamine) gradually decreased above the critical fluorine concentration (0.02797 wt %). However, for the blending of the FAPUD 25Na series (neutralization with sodium carbonate), the surface energy increased above the critical fluorine concentration (0.02797 wt %) because of the increase in Na salts. The FAPUDs showed the native thermal behavior of the fluorine. However, the thermal properties of the blending films were like those of pure PUDs. This showed that the morphology of the PUDs was rarely unchanged when the FAPUDs were added. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3322–3330, 2002
Effect of poly(vinyl chloride) resin type in the preparation process of slush powder
Authors: Luo Yuxiang , Dai Gance
Published: October 2002

During the preparation of the poly(vinyl chloride) (PVC) slush powder, we found that PVC resins obtained by different polymerization methods affected many properties of slush powder and its products. Two types of commercial PVC resins were used for slush powder preparation: mass poly(vinyl chloride) (M‐PVC) and suspension poly(vinyl chloride) (S‐PVC). We used the Haake rheomix test to characterize the absorption of plasticizers into PVC resins, and the results showed that M‐PVC absorbed the plasticizers more quickly than S‐PVC. The fusion behavior of the two slush powders was studied by the thermal plate test and Haake rheomix test, and the results showed that the slush powder of M‐PVC was easier to fuse than that of S‐PVC. The different properties of the two resins and slush powder could be explained by the morphology, average size, and size distribution. Due to the “skin” of the particles' surfaces, the wider size distribution, and the large size of particles, S‐PVC absorbed the plasticizers more slowly and was more difficult to fuse. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3331–3335, 2002
Human serum albumin (HSA) adsorption with chitosan microspheres
Authors: Denkbas Emir Baki , Odabasi Mehmet , Kiliçay Ebru , Özdemir Nalan
Published: October 2002

In this study, chitosan microspheres were prepared and characterized for adsorption of human serum albumin (HSA) as affinity sorbent. The chitosan microspheres were obtained with a “suspension crosslinking technique” in the size range of 30–700 μm by using a crosslinker, i.e., glutaraldehyde. The chitosan microspheres used in HSA adsorption studies were having the average size of 170 ± 81 μm. Adsorption medium pH and the initial HSA concentration in the adsorption medium were changed as 4.0–7.0 and 0.5–2.0 mg HSA/mL, respectively, to investigate the HSA adsorption capacity of chitosan microspheres. Maximum HSA adsorption (i.e., 11.35 mg HSA/g chitosan microspheres) was obtained at pH 5.0 and 1.5 mg HSA/mL of the initial HSA concentration in the adsorption medium was obtained as the saturation value for HSA adsorption. A very common dye ligand, i.e., Cibacron Blue F3GA was attached to the chitosan microspheres to increase the HSA adsorption capacity. Actually, the HSA adsorption capacity was increased up to 15.35 mg HSA/g chitosan microspheres in the case of Cibacron Blue F3GA attached to chitosan microspheres used. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3035–3039, 2002