Phase diagram of the vortex system in layered superconductors with strong columnar pinning

We present the results of a detailed investigation of the low-temperature properties of the vortex system in strongly anisotropic layered superconductors with a random array of columnar pinning centers. Our method involves numerical minimization of a free energy functional in terms of the time-averaged local vortex density. It yields the detailed vortex density distribution for all local free-energy minima, and therefore allows the computation of any desired correlation function of the time-averaged local vortex density. Results for the phase diagram in the temperature vs. pin concentration plane at constant magnetic induction are presented. We confirm that for very low pin concentrations, the low-temperature phase is a Bragg glass, which melts into an interstitial liquid phase via two first-order steps, separated by a Bose glass phase. At higher concentrations, however, the low-temperature phase is a Bose glass, and the melting transition becomes continuous. The transition is then characterized by the onset of percolation of liquid-like regions across the sample. Inhomogeneous local melting of the Bose glass is found to occur. There is also a depinning crossover between the interstitial liquid and a completely unpinned liquid at higher temperatures. At sufficiently large pin concentrations, the depinning line merges with the Bose glass to interstitial liquid transition. Many of the features we find have been observed experimentally and in simulations. We discuss the implications of our results for future experimental and theoretical work.Comment: 15 pages including Figure

The phase diagram of vortex matter in layered superconductors with tilted columnar pinning centers

We study the vortex matter phase diagram of a layered superconductor in the presence of columnar pinning defects, {\it tilted} with respect to the normal to the layers. We use numerical minimization of the free energy written as a functional of the time averaged vortex density of the Ramakrishnan-Yussouff form, supplemented by the appropriate pinning potential. We study the case where the pin density is smaller than the areal vortex density. At lower pin concentrations, we find, for temperatures of the order of the melting temperature of the unpinned lattice, a Bose glass type phase which at lower temperatures converts, via a first order transition, to a Bragg glass, while, at higher temperatures, it crosses over to an interstitial liquid. At somewhat higher concentrations, no transition to a Bragg glass is found even at the lowest temperatures studied. While qualitatively the behavior we find is similar to that obtained using the same procedures for columnar pins normal to the layers, there are important and observable quantitative differences, which we discuss.Comment: 12 pages, including figure

Phase diagram of vortex matter in layered superconductors with random point pinning

We study the phase diagram of the superconducting vortex system in layered high-temperature superconductors in the presence of a magnetic field perpendicular to the layers and of random atomic scale point pinning centers. We consider the highly anisotropic limit where the pancake vortices on different layer are coupled only by their electromagnetic interaction. The free energy of the vortex system is then represented as a Ramakrishnan-Yussouff free energy functional of the time averaged vortex density. We numerically minimize this functional and examine the properties of the resulting phases. We find that, in the temperature ($T$) -- pinning strength ($s$) plane at constant magnetic induction, the equilibrium phase at low $T$ and $s$ is a Bragg glass. As one increases $s$ or $T$ a first order phase transition occurs to another phase that we characterize as a pinned vortex liquid. The weakly pinned vortex liquid obtained for high $T$ and small $s$ smoothly crosses over to the strongly pinned vortex liquid as $T$ is decreased or $s$ increased -- we do not find evidence for the existence, in thermodynamic equilibrium, of a distinct vortex glass phase in the range of pinning parameters considered here. %cdr We present results for the density correlation functions, the density and defect distributions, and the local field distribution accessible via $\mu$SR experiments. These results are compared with those of existing theoretical, numerical and experimental studies.Comment: 15 pages, including figures. Higher resolution files for Figs 3a and 11 available from author

Heterosis and inbreeding depression to identify superior F1 hybrids in tomato (Solanum lycopersicum L.) for the yield and its contributing traits

Eight parental lines of diverse origin of tomato (Solanum lycopersicum L.) were crossed in 8 × 8 diallel mating design excluding reciprocals. The 28 F1 hybrids along with their parents and one standard check (H-86) were evaluated in a randomized block design with three replications during seasons of rabi 2011-12, 2012-13 and 2013-14. In the present study, revealed that heterosis over better parent, mid parent, standard check and inbreeding depression was observed for all the traits under studies. Highly significant heterosis was observed for days to first flowering (-13.49, -13.52 and -12.28%), number of flowers per cluster (17.90, 22.11 and 24.27%), days to first harvest (-8.01, -11.04 and -9.76%), number of fruit per cluster (39.17, 42.71 and 20.71%), fruit diameter (19.93, 31.43 and 13.27%), fruit length (19.29, 22.34 and 13.35%), Average fruit weight (18.88, 19.41 and 7.80%), number of fruits per plant (25.86, 46.69 and 41.87%) and yield per plant (58.61, 75.61 and 56.33%) over the better, mid and standard parents, respectively along with considerable inbreeding depression. Most promising cross Pant T-3 × H-24 showed highly significant positive heterosis over better parent for yield per plant

Estimation of combining ability analysis in tomato (Solanum lycopersicum L.) for yield, nutritional and processing quality improvement

Combining ability for yield and nutritional quality traits in tomato were studied by involving 28 cross combi-nations obtained from crossing 8 diverse lines in diallel mating fashion. Based on GCA effects of parents, the varie-ties Pant T-3, Arka Alok and Sel-7 were good general combiners for most of the traits under study. The crosses viz., Pant T-3 x H-24 (1.052%), Arka Meghali x Punjab Chhuhara (0.768%) and H-88-78-1 x Azad T-5 (0.768%) were found to be high positive specific combining ability effect for yield per plant. For quality traits, the crosses Arka Me-ghali x Punjab Chhuhara and H-24 x Sel-7 were also superior specific combiner for number of seeds per fruit and ascorbic acid, while cross Punjab Chhuhara x H-88-78-1 was superior specific combiner for number of seeds per fruit (24.165%), yield per plant (0.677%) and titrable acidity (0.183%). These elite hybrids may be tested for yield and other quality traits under different agro-climatic conditions for commercial exploitation of hybrid vigour

Melting and structure of the vortex solid in strongly anisotropic layered superconductors with random columnar pins

We study the melting transition of the low-temperature vortex solid in strongly anisotropic layered superconductors with a concentration of random columnar pinning centers small enough so that the areal density of the pins is much less than that of the vortex lines. Both the external magnetic field and the columnar pins are assumed to be oriented perpendicular to the layers Our method, involving numerical minimization of a model free energy functional, yields not only the free energy values at the local minima of the functional but also the detailed density distribution of the system at each minimum: this allows us to study in detail the structure of the different phases. We find that at these pin concentrations and low temperatures, the thermodynamically stable state is a topologically ordered Bragg glass. This nearly crystalline state melts into an interstitial liquid (a liquid in which a small fraction of vortex lines remain localized at the pinning centers) in two steps, so that the Bragg glass and the liquid are separated by a narrow phase that we identify from analysis of its density structure as a polycrystalline Bose glass. Both the Bragg glass to Bose glass and the Bose glass to interstitial liquid transitions are first-order. We also find that a local melting temperature defined using a criterion based on the degree of localization of the vortex lines exhibits spatial variations similar to those observed in recent experiments.Comment: 17 page

Quantum hysteresis loops in microscopic system: the loop area as a dynamical parameter

The area enclosed by hysteresis loops in a periodically forced bistable microscopic system at zero-temperature is examined by using the time dependent Hellmann-Feynman theorem and the Fourier grid Hamiltonian recipe for solving time-dependent Schrodinger equation. Effects of non-zero temperatures are explored with reference to a symmetric double well potential. The barrier crossing or, relaxation rates are shown to correlate systematically with the area of the loop. The possible use of hysteresis loop area in designing field parameters for optimal control is suggested