Onset of phase correlations in YBa2Cu3O{7-x} as determined from reversible magnetization measurements

Isofield magnetization curves are obtained and analyzed for three single crystals of YBa2Cu3O{7-x}, ranging from optimally doped to very underdoped, as well as the BCS superconductor Nb, in the presence of magnetic fields applied both parallel and perpendicular to the $ab$ planes. Near Tc, the magnetization exhibits a temperature dependence \sqrt{M} [Ta(H)-T]^m. In accordance with recent theories, we associated Ta(H) with the onset of coherent phase fluctuations of the superconducting order parameter. For Nb and optimally doped YBaCuO, Ta(H) is essentially identical to the mean-field transition line Tc(H). The fitting exponent m=0.5 takes its mean-field value for Nb, and varies just slightly from 0.5 for optimally doped YBaCuO. However, underdoped YBCO samples exhibit anomalous behavior, with Ta(H)>Tc for H applied parallel to the c axis, suggesting that the magnetization is probing a region of temperatures above Tc where phase correlations persist. In this region, the fitting exponent falls in the range 0.5 < m < 0.8 for H\parallel c, compared with m~0. for $H\parallel ab planes. The results are interpreted in terms of an anisotropic pairing symmetry of the order parameter: d-wave along the ab planes and s-wave along the c axis.Comment: 5 pages, 4 figure

Landau and Ott scaling for the kinetic energy density and the low TcT_c conventional superconductors, Li2Pd3BLi_{2}Pd_{3}B and Nb

The scaling approach recently proposed by Landau and Ott for isothermal magnetization curves is extended to the average kinetic energy density of the condensate. Two low $T_c$ superconductors, Nb and $Li_{2}Pd_{3}B$ are studied and their isothermal reversible magnetization shown to display Landau and Ott scaling. Good agreement is obtained for the upper critical field $H_{c2}(T)$, determined from the Abrikosov approximation for the reversible region (standard linear extrapolation of the magnetization curve), and from the maximum of the kinetic energy curves. For the full range of data, which includes the irreversible region, the isothermal $d.M.B/H^2$ curves for $Li_2Pd_3B$ show an impressive collapse into a single curve over the entire range of field measurements. The Nb isothermal $d.M.B/H^2$ curves exhibit the interesting feature of a constant and temperature independent minimum value

A Robust Solution Procedure for Hyperelastic Solids with Large Boundary Deformation

Compressible Mooney-Rivlin theory has been used to model hyperelastic solids, such as rubber and porous polymers, and more recently for the modeling of soft tissues for biomedical tissues, undergoing large elastic deformations. We propose a solution procedure for Lagrangian finite element discretization of a static nonlinear compressible Mooney-Rivlin hyperelastic solid. We consider the case in which the boundary condition is a large prescribed deformation, so that mesh tangling becomes an obstacle for straightforward algorithms. Our solution procedure involves a largely geometric procedure to untangle the mesh: solution of a sequence of linear systems to obtain initial guesses for interior nodal positions for which no element is inverted. After the mesh is untangled, we take Newton iterations to converge to a mechanical equilibrium. The Newton iterations are safeguarded by a line search similar to one used in optimization. Our computational results indicate that the algorithm is up to 70 times faster than a straightforward Newton continuation procedure and is also more robust (i.e., able to tolerate much larger deformations). For a few extremely large deformations, the deformed mesh could only be computed through the use of an expensive Newton continuation method while using a tight convergence tolerance and taking very small steps.Comment: Revision of earlier version of paper. Submitted for publication in Engineering with Computers on 9 September 2010. Accepted for publication on 20 May 2011. Published online 11 June 2011. The final publication is available at http://www.springerlink.co

Experimental observation of two-dimensional fluctuation magnetization in the vicinity of T_c for low values of the magnetic field in deoxygenated YBa_2Cu_3O_{7-x}

We measured isofield magnetization curves as a function of temperature in two single crystal of deoxygenated YBaCuO with T_c = 52 and 41.5 K. Isofield MvsT were obtained for fields running from 0.05 to 4 kOe. The reversible region of the magnetization curves was analyzed in terms of a scaling proposed by Prange, but searching for the best exponent $\upsilon$. The scaling analysis carried out for each data sample set with $\upsilon$=0.669, which corresponds to the 3D-xy exponent, did not produced a collapsing of curves when applied to MvsT curves data obtained for the lowest fields. The resulting analysis for the Y123 crystal with T_c = 41.5 K, shows that lower field curves collapse over the entire reversible region following the Prange's scaling with $\upsilon$=1, suggesting a two-dimensional behavior. It is shown that the same data obeying the Prange's scaling with $\upsilon$=1 for crystal with T_c = 41.5 K, as well low field data for crystal with $T_c$ = 52 K, obey the known two-dimensional scaling law obtained in the lowest-Landau-level approximation.Comment: 4 pages, 3 figure

A comparative study of high-field diamagnetic fluctuations in deoxygenated YBa2Cu3O(7-x) and polycrystalline (Bi-Pb)2Sr2Ca3O(10)

We studied three single crystals of YBa2Cu3O{7-x} with Tc= 62.5, 52, and 41 K, and a textured specimen of (Bi-Pb)2Sr2Ca2Cu3O10 with Tc=108 K, for H//c axis. The reversible data were interpreted in terms of 2D lowest-Landau-level fluctuation theory. The data were fit well by the 2D LLL expression for magnetization obtained by Tesanovic etal., producing reasonable values of kappa but larger values of dHc2/dT. Universality was studied by obtaining a simultaneous scaling of Y123 data and Bi2223. An expression for the 2D x-axis LLL scaling factor used to obtain the simultaneous scaling was extracted from theory, and compared with the experimental values. The comparison between the values of the x-axis produced a deviation of 40% which suggests that the hypothesis of universality of the 2D-LLL fluctuations is not supported by the studied samples. We finaly observe that Y123 magnetization data for temperatures above $T_c$ obbey a universal scaling obtained for the diamagnetic fluctuation magnetization from a theory considering non-local field effects. The same scaling was not obbeyed by the corresponding magnetization calculated from the two-dimensional lowest-Landau-level theory.Comment: 7 pages 5 figures, accept in Journ. Low Temp. Phy

Non-centro-symmetric superconductors Li2Pd3B and Li2(Pd0.8Pt0.2)3B: amplitude and phase fluctuations analysis of the experimental magnetization data

We report on magnetization data obtained as a function of temperature and magnetic field in Li2 (Pd0.8Pt0.2)3B and Li2Pd3B non-centro-symmetric superconductors. Reversible magnetization curves were plotted as M1/2 vs. T. This allows study of the asymptotic behavior of the averaged order parameter amplitude (gap) near the superconducting transition. Results of the analysis show, as expected, a mean field superconducting transition for Li2Pd3B. On contrary, a large deviation from the mean field behavior is revealed for Li2(Pd0.8Pt0.2)3B. This is interpreted as due to the strength of the non s-wave spin-triplet pairing in this Pt-containing compound which produces nodes in the order parameter and consequently, phase fluctuations. The diamagnetic signal above Tc(H) in Li2Pd3B is well explained by superconducting Gaussian fluctuations, which agrees with the observed mean field transition. For Li2(Pd0.8Pt0.2)3B the diamagnetic signal above Tc(H) is much higher than the expected Gaussian values and appears to be well explained by three dimensional critical fluctuations of the lowest-Landau-level type, which somehow agrees with the scenario of a phase mediated transition.Comment: 7 pages (1 column) 3 figure

Branding fashion through gameplay: the branded gaming and the cool dynamics in the fashion markets. A game-theory approach

Purpose The aim of this study was to investigate the role of immersive gaming on brand coolness and brand equity, with particular emphasis on fashion gaming collaborations. We used game theory as a theoretical framework to analyse immersive branding strategies and gain a deeper understanding of fashion consumers’ decision-making process in gaming environments. Gender, as a significant factor affecting gamers, has been studied as a moderator that impacts the overall proposed framework. Design/methodology/approach A quantitative method was used to assess the significance of relationships within the proposed model empirically. The partial least squares structural equation modelling technique was implemented to assess the relationships of the framework with a sample size of 160 active Malaysian gamers. Findings The findings indicate that brand equity is positively associated with perceived brand coolness. Furthermore, of the three core values of online games, perceived enjoyment is most strongly associated with perceived brand coolness, ahead of the values of self-expression and perceived emotional challenge. The results of the multigroup analysis further suggest that in the fashion industry, building brand equity through online games is strongly related to perceived brand coolness among female respondents, the role of perceived brand coolness being weaker among male respondents. Originality/value The study contributes to the existing literature by providing a deeper understanding of the impact of immersive gaming branding practices on the overall equity of the fashion brand. The results provide insight for fashion brand managers into the significant effect on consumer behaviour outcomes of fashion-gaming collaborations.研究目的 本研究擬探討身歷其境的遊戲體驗在品牌酷感和品牌資產上所扮演的角色; 研究特別強調裝扮遊戲的合作。研究人員以博弈論作為研究的理論框架,來分析沉浸品牌策略、和對時裝消費者在遊戲的環境中如何作出決策取得更深入的瞭解。研究人員探討了性別作為影響遊戲參與者的重要因素,這因素被視為為整個被提出的框架帶來調節的影響和作用。 研究設計/方法/理念 研究人員採用定量方法進行研究,目的為於被提出的模型內之各種關聯的意義進行以經驗為依據的評估。研究人員採用了基於偏最小平方法的結構方程模型研究法,來對一個包含160名活躍的馬來西亞遊戲參與者的樣本進行框架的各個聯繫的評估研究。 研究結果 研究結果顯示,品牌資產與品牌酷感成正相關; 而且,在網絡遊戲的三個核心價值中,感知享受與品牌酷感之間的聯繫最為強烈和密切,超過自我表現和感知情感挑戰兩者的價值; 多群組的分析結果更暗示了在時裝產業裡,透過網絡遊戲去建立品牌資產在女性回應者中是與品牌酷感有強烈密切的關係; 而在男性回應者中,品牌酷感所扮演的角色則較弱。 研究的原創性/價值 本研究使我們能更深入認識沉浸遊戲品牌的慣常做法如何影響時裝品牌的整體資產。研究結果為時裝品牌經理提供了啟示,使他們明瞭時裝遊戲的合作會給消費者行為產生重要的影響