Comparative foliar anatomical study of six different varieties of Piper betle L.

The present investigation on a few selected cultivars of Piper betle L. was undertaken mainly to understand the anatomy and tissue components of the stem, leaves and petiole. This was accomplished by using basic anatomy techniques such as free hand and microtome sectioning. The varieties selected were: HY1, HY2, JB, KB, LV and SG. Major aspects of the present inquiry were - macro morphology, anatomy and histochemistry. The main focus of the study was on the internal structure of leaves and petioles to understand the role of specialised cells like enlarged hypodermal cells and mucilage cavities in retaining moisture and thereby preserving the shelf life of harvested leaves

Temperature - pressure phase diagram of the superconducting iron pnictide LiFeP

Electrical-resistivity and magnetic-susceptibility measurements under hydrostatic pressure up to p = 2.75 GPa have been performed on superconducting LiFeP. A broad superconducting (SC) region exists in the temperature - pressure (T-p) phase diagram. No indications for a spin-density-wave transition have been found, but an enhanced resistivity coefficient at low pressures hints at the presence of magnetic fluctuations. Our results show that the superconducting state in LiFeP is more robust than in the isostructural and isoelectronic LiFeAs. We suggest that this finding is related to the nearly regular [FeP_4] tetrahedron in LiFeP.Comment: 4 pages, 4 figure

PHYTOCHEMICAL ANALYSIS OF SOME SELECTED VARIETIES OF PIPER BETLE L.

Objective: To Analyse the major phytochemical components in selected varieties of P. betle leaves using GC-MS.Methods: P. betle leaves were shade dried and pulverized to powder in a mechanical grinder. The powder was successively extracted with ethanol (40-60 °C). The extracts were concentrated under reduced pressure in a rotary evaporator. The ethanolic extracts of the plant leaves were used for GC-MS analysis.Results: In the present study ten chemicals were identified and compared from the P. betle varieties, the major component being Eugenol, which is responsible for the flavour and aroma of the leaves.Conclusion: Variety Karpoori possesses the highest content of Eugenol and could be used as a promising variety in the pharmaceutical industry. The components of essential oil can also serve as a determinant to distinguish different varieties of betle vine cultivars

Hydrostatic and chemical pressure tuning of CeFeAs1−xPxO single crystals

We carried out a combined P-substitution and hydrostatic pressure study on CeFeAs_1-xP_xO single crystals in order to investigate the peculiar relationship of the local moment magnetism of Ce, the ordering of itinerant Fe moments, and their connection with the occurrence of superconductivity. Our results evidence a close relationship between the weakening of Fe magnetism and the change from antiferromagnetic to ferromagnetic ordering of Ce moments at p*=1.95 GPa in CeFeAs_0.78P_0.22O. The absence of superconductivity in CeFeAs_0.78P_0.22O and the presence of a narrow and strongly pressure sensitive superconducting phase in CeFeAs_0.70P_0.30O and CeFeAs_0.65P_0.35O indicate the detrimental effect of the Ce magnetism on superconductivity in P-substituted CeFeAsO.Comment: 5 pages, 4 figure

Pressure-induced ferromagnetism due to an anisotropic electronic topological transition in Fe1.08Te

A rapid and anisotropic modification of the Fermi-surface shape can be associated with abrupt changes in crystalline lattice geometry or in the magnetic state of a material. In this study we show that such an electronic topological transition is at the basis of the formation of an unusual pressure-induced tetragonal ferromagnetic phase in Fe$_{1.08}$Te. Around 2 GPa, the orthorhombic and incommensurate antiferromagnetic ground-state of Fe$_{1.08}$Te is transformed upon increasing pressure into a tetragonal ferromagnetic state via a conventional first-order transition. On the other hand, an isostructural transition takes place from the paramagnetic high-temperature state into the ferromagnetic phase as a rare case of a `type 0' transformation with anisotropic properties. Electronic-structure calculations in combination with electrical resistivity, magnetization, and x-ray diffraction experiments show that the electronic system of Fe$_{1.08}$Te is instable with respect to profound topological transitions that can drive fundamental changes of the lattice anisotropy and the associated magnetic order.Comment: 7 pages, 4 figur

Possible unconventional superconductivity in substituted BaFe2_{2}As2_{2} revealed by magnetic pair-breaking studies

The possible existence of a sign-changing gap symmetry in BaFe$_{2}$As$_{2}$-derived superconductors (SC) has been an exciting topic of research in the last few years. To further investigate this subject we combine Electron Spin Resonance (ESR) and pressure-dependent transport measurements to investigate magnetic pair-breaking effects on BaFe$_{1.9}M_{0.1}$As$_{2}$ ($M=$ Mn, Co, Cu, and Ni) single crystals. An ESR signal, indicative of the presence of localized magnetic moments, is observed only for $M=$ Cu and Mn compounds, which display very low SC transition temperature ($T_{c}$) and no SC, respectively. From the ESR analysis assuming the absence of bottleneck effects, the microscopic parameters are extracted to show that this reduction of $T_{c}$ cannot be accounted by the Abrikosov-Gorkov pair-breaking expression for a sign-preserving gap function. Our results reveal an unconventional spin- and pressure-dependent pair-breaking effect and impose strong constraints on the pairing symmetry of these materials

Possible Unconventional Superconductivity In Substituted Bafe 2 As 2 Revealed By Magnetic Pair-breaking Studies

The possible existence of a sign-changing gap symmetry in BaFe 2 As 2 -derived superconductors (SC) has been an exciting topic of research in the last few years. To further investigate this subject we combine Electron Spin Resonance (ESR) and pressure-dependent transport measurements to investigate magnetic pair-breaking effects on BaFe 1.9 M 0.1 As 2 (M = Mn, Co, Cu, and Ni) single crystals. An ESR signal, indicative of the presence of localized magnetic moments, is observed only for M = Cu and Mn compounds, which display very low SC transition temperature (T c) and no SC, respectively. From the ESR analysis assuming the absence of bottleneck effects, the microscopic parameters are extracted to show that this reduction of T c cannot be accounted by the Abrikosov-Gorkov pair-breaking expression for a sign-preserving gap function. Our results reveal an unconventional spin- and pressure-dependent pair-breaking effect and impose strong constraints on the pairing symmetry of these materials.4Kamihara, Y., Watanabe, T., Hirano, M., Hosono, H., Iron-based layered superconductor La[O12xFx]FeAs (x 5 0. 05-0. 12) with Tc 5 26 K (2008) J. Am. Chem. Soc., 130, p. 3296Rotter, M., Spin density wave anomaly at 140 K in the ternary iron arsenide BaFe2As2 (2008) Phys. Rev. B, 78, pp. 020503RIshida, K., Nakai, Y., Hosono, H., To what extent iron-pnictide new superconductors have been clarified: A progress report (2009) J. Phys. Soc. Japan, 78, p. 062001Hirschfeld, P.J., Korshunov, M.M., Mazin, I.I., Gap symmetry and structure of Fe-based superconductors (2011) Rep. Prog. Phys., 74, p. 124508Chubukov, A.V., Pairing mechanism in fe-based superconductors (2012) Annu. Rev. Cond. Mat. Phys., 3, p. 57Bittar, E.M., Co-substitution effects on the fe valence in the BaFe2As2 superconducting compound: A study of hard x-ray absorption spectroscopy (2011) Phys. Rev. Lett., 107, p. 267402Granado, E., Pressure and chemical substitution effects in the local atomic structure of BaFe2As2 (2011) Phys. Rev. B, 83, p. 184508Wadati, H., Elfimov, I., Sawatzky, G.A., Where are the extra d electrons in transition-metal-substituted iron pnictides? (2010) Phys. Rev. Lett., 105, p. 157004Ideta, S., Dependence of carrier doping on the impurity potential in transition-metal-substituted feas-based superconductors (2013) Phys. Rev. Lett., 110, p. 107007Berlijn, T., Lin, C.-H., Garber, W., Ku, W., Do transition-metal substitutions dope carriers in iron-based superconductors? (2012) Phys. Rev. Lett., 108, p. 207003Hin, Z.P., Haule, K., Kotliar, G., Kinetic frustration and the nature of the magnetic and paramagnetic states in iron pnictides and iron chalcogenides (2011) Nature Materials, 10, pp. 932a-935aRosa, P.F.S., Evolution of Eu21 spin dynamics in Ba12xEuxFe2As2 (2012) Phys. Rev. B, 86, p. 165131Rosa, P.F.S., (2014) Site Specific Spin Dynamics in BaFe2As2: Tuning the Ground State by Orbital Differentiation, , arxiv:1402. 2001v01Garitezi, T.M., Transport critical current measurements on a Cu-substituted BaFe2As2 superconductor (2014) J. Appl. Phys., 115, pp. 17D704Rosa, P.F.S., Pressure effects on magnetic pair-breaking in Mn- and Eusubstituted BaFe2As2 (2014) J. Appl. Phys., 115, pp. 17D702Thaler, A., Physical and magnetic properties of Ba(Fe12xMnx) 2As2 single crystals (2011) Phys. Rev. B, 84, p. 144528Et Al., A., Pressure effects on the electron-doped high Tc superconductor BaFe22xCoxAs2 (2008) J Phys. Cond. Mat., 20, p. 472201Et Al., D., Pressure versus concentration tuning of the superconductivity in Ba(Fe12xCox) 2As2 (2010) J. Phys. Soc. Japan, 79, p. 124705Yamaichi, S., Katagiri, T., Sasagawa, T., Uniaxial pressure effects on the transport properties in Ba(Fe12xCox) 2As2 single crystals (2013) Physica C, 494, pp. 62-64Canfield, P.C., Budko, S.L., Ni, N., Yan, J.Q., Kracher, A., Decoupling of the superconducting and magnetic/structural phase transitions in electron-doped BaFe2As2 (2009) Phys. Rev. B, 80, pp. 060501RKirshenbaum, K., Saha, S.R., Ziemak, S., Drye, T., Paglione, J., Universal pairbreaking in transition metal-substituted iron-pnictide superconductors (2012) Phys. Rev. B, 86, pp. 140505ROnari, S., Kontani, H., Violation of Andersonaŝ Theorem for the Sign-Reversing s-Wave State of Iron-Pnictide Superconductors (2009) Phys. Rev. Lett., 103, p. 177001Li, J., Superconductivity suppression of Ba0. 5K0. 5Fe222xMn2xAs2 single crystals by substitution of transition metal (M 5 Mn, Ru, Co, Ni, Cu, and Zn) (2012) Phys. Rev. B, 85, p. 214509Bang, Y., Choi, H.-Y., Won, H., Impurity effects on the s6-wave state of the ironbased superconductors (2009) Phys. Rev. B, 79, p. 054529Wang, Y., Kreisel, A., Hirschfeld, P.J., Mishra, V., Using controlled disorder to distinguish s6 and s11 gap structure in Fe-based superconductors (2013) Phys. Rev. B, 87, p. 094504Fernandes, R.M., Vavilov, M.G., Chubukov, A.V., Enhancement of Tc by disorder in underdoped iron pnictide superconductors (2012) Phys. Rev. B, 85, pp. 140512RNi, N., Temperature versus doping phase diagrams for Ba(Fe12xTMx) 2As2 (TM 5 Ni,Cu,Cu/Co) single crystals (2010) Phys. Rev. B, 82, p. 024519Patz, A., Ultrafast observation of critical nematic fluctuations and giant magnetoelastic coupling in iron pnictides (2014) Nature Comm., 5, p. 3229Abrikosov, A.A., Gorkov, L.P., Contribution to the theory of superconducting alloys with paramagnetic impurities (1961) Sov. Phys. JETP, 12, p. 1243Skalski, S., Betbeder-Matibet, O., Weiss, P.R., Properties of superconducting alloys containing paramagnetic impurities (1964) Phys. Rev., 136, pp. A1500-A1518Pagliuso, P.G., Electron spin resonance of Gd31 in the normal state of RNi2B2C (R 5 Y, Lu) (1998) Phys. Rev. B, 57, p. 3668Korringa, J., Nuclear magnetic relaxation and resonance line shift in metals (1950) Physica, 16, p. 601Rettori, C., Dynamic behavior of paramagnetic ions and conduction electrons in intermetallic compounds: GdxLu12xAl2 (1974) Phys. Rev. B, 10, p. 1826Davidov, D., Electron spin resonance of Gd in the intermetallic compounds YCu, YAg, and LaAg:Wave vector dependence of the exchange interaction (1973) Solid State Comm., 12, p. 621Narath, A., Weaver, H.T., Effects of electron-electron interactions on nuclear spin-lattice relaxation rates and knight shifts in alkali and noble metals (1968) Phys. Rev., 175, p. 373Shaw, R.W., Warren, W.W., Enhancement of the korringa constant in alkali metals by electron-electron interactions (1971) Phys. Rev. B, 3, p. 1562Bittar, E.M., Electron spin resonance study of the LaIn32xSnx superconducting system (2011) J. of Phys.: Cond. Matt., 23, p. 455701Maple, M.B., Dependence of s 2 f exchange on atomic number in rare earth dialuminides (1970) Solid State Comm., 8 (22), pp. 1915-1917Garitezi, T.M., Synthesis and characterization of BaFe2As2 single crystals grown by in-flux technique (2013) Brazilian Journal of Physics, 43, p. 223Alireza, P.L., Superconductivity up to 29 K in SrFe2As2 and BaFe2As2 at high pressures (2009) J. Phys. Condens. Matter, 21, p. 012208Rotter, M., Tegel, M., Johrendt, D., Superconductivity at 38 K in the Iron Arsenide Ba12xKxFe2As2 (2008) Phys. Rev. Lett., 101, p. 107006Wang, C., Thorium-dopingaînduced superconductivity up to 56âK in Gd12xThxFeAsO (2008) EPL, 83, p. 67006Shibata, A., Thorium-dopingaînduced superconductivity up to 56âK in Gd12xThxFeAsO (1986) J. Phys. Soc. Jpn., 55, p. 6Cooley, J.C., Aronson, M.C., Canfield, P.C., High pressures and the Kondo gap in Ce3Bi4Pt3 (1997) Phys. Rev. B, 55, p. 7533Oomi, G., Kagayama, T., Effect of pressure and magnetic field on the electrical resistivity of cerium kondo compounds (1996) J. Phys. Soc. Jpn., 65 (SUPPL. B), pp. 42-48Ramos, S.M., Superconducting quantum critical point in CeCoIn52xSnx (2010) Phys. Rev. Lett., 105, p. 126401Hering, E.N., Pressureâtemperatureâcomposition phase diagram of Ce2MIn8 (2006) Physica B: Cond. Matt., 378Dyson, F.J., Electron spin resonance absorption in metals. Ii. Theory of electron diffusion and the skin effect (1955) Phys. Rev., 98, p. 349Texier, Y., Mn local moments prevent superconductivity in iron pnictides Ba(Fe12xMnx) 2As2 (2012) EPL, 99, p. 17002Leboeuf, D., (2013) NMR Study of Electronic Correlations in Mn-doped Ba(Fe12xCox) 2As2 and BaFe(As12xPx) 2, p. 4969. , arXiv1310Suzuki, H., Absence of superconductivity in the hole-doped Fe pnictide Ba(Fe12xMnx) 2As2: Photoemission and x-ray absorption spectroscopy studies (2013) Phys. Rev. B, 88, pp. 100501RKim, M.G., Effects of transition metal substitutions on the incommensurability and spin fluctuations in BaFe2As2 by elastic and inelastic neutron scattering (2012) Phys. Rev. Lett., 109, p. 167003Et Al., F., Short-range magnetic order and effective suppression of superconductivity by manganese doping in LaFe12xMnxAsO12yFy (2013) Phys. Rev. B, 87, p. 174515Golubov, A.A., Mazin, I.I., Effect of magnetic and nonmagnetic impurities on highly anisotropic superconductivity (1997) Phys. Rev. B, 55, p. 15146Openov, L.A., Combined effect of nonmagnetic and magnetic scatterers on the critical temperatures of superconductors with different anisotropies of the gap (1997) JETP Lett., 66, p. 661Efremov, D.V., Disorder-induced transition between s6 and s11 states in two-band superconductors (2011) Phys. Rev. B, 84, p. 180512Tucker, G.S., Competition between stripe and checkerboard magnetic instabilities in Mn-doped BaFe2As2 (2012) Phys. Rev. B, 86, p. 020503Fernandes, R.M., Millis, A.J., Suppression of Superconductivity by Neel-Type magnetic fluctuations in the iron pnictides (2013) Phys. Rev. Lett., 110, p. 117004Chi, S., (2013) Sign Inversion in the Superconducting Order Parameter of LiFeAs Inferred from Bogoliubov Quasiparticle Interference. ArXiv:1308. 4413v1Johnston, D.C., (2010) Adv. Phys., 59, p. 803Paglione, J., Greene, R.L., Hightemperature superconductivity in iron-based materials (2010) Nature Phys., 6, p. 645Wen, H.H., Li, S., Materials and novel superconductivity in iron pnictide superconductors (2011) Annu. Rev. Cond. Mat. Phys., 2, p. 121Stewart, G.R., Superconductivity in iron compounds (2011) Rev. Mod. Phys., 83, pp. 1589-165

Electron Doping of the Iron-Arsenide Superconductor CeFeAsO Controlled by Hydrostatic Pressure

In the iron-pnictide material CeFeAsO not only the Fe moments, but also the local 4f moments of the Ce order antiferromagnetically at low temperatures. We elucidate on the peculiar role of the Ce on the emergence of superconductivity. While application of pressure suppresses the iron SDW ordering temperature monotonously up to 4 GPa, the Ce-4f magnetism is stabilized, until both types of magnetic orders disappear abruptly and a narrow SC dome develops. With further increasing pressure characteristics of a Kondo-lattice system become more and more apparent in the electrical resistivity. This suggests a connection of the emergence of superconductivity with the extinction of the magnetic order and the onset of Kondo-screening of the Ce-4f moments.Comment: 6 pages, 3 figures + supplemental materia

Pressure Tuning of Superconductivity of LaPt₄Ge₁₂ and PrPt₄Ge₁₂ Single Crystals

We carried out electrical resistivity and X-ray diffraction (XRD) studies on the filled skutterudite superconductors LaPt4Ge12 and PrPt(4)Ge(12 )under hydrostatic pressure. The superconducting transition temperature T-c is linearly suppressed upon increasing pressure, though the effect of pressure on T-c is rather weak. From the analysis of the XRD data, we obtain bulk moduli of B = 106 GPa and B = 83 GPa for LaPt4Ge12 and PrPt4Ge12, respectively. The knowledge of the bulk modulus allows us to compare the dependence of T-c on the unit-cell volume from our pressure study directly with that found in the substitution series La1-xPrxPt4Ge12. We find that application of hydrostatic pressure can be characterized mainly as a volume effect in LaPt4Ge12 and PrPt4Ge12, while substitution of Pr for La1-xPrxPt4Ge12 yields features going beyond a simple picture