Unconventional superconductivity in the cage type compound Sc5_5Rh6_6Sn18_{18}

We have examined the superconducting ground state properties of the caged type compound Sc$_5$Rh$_6$Sn$_{18}$ using magnetization, heat capacity, and muon-spin relaxation or rotation ($\mu$SR) measurements. Magnetization measurements indicate type-II superconductivity with an upper critical field $\mu_0H_{c2}(0)$ = 7.24 T. The zero-field cooled and field cooled susceptibility measurements unveil an onset of diamagnetic signal below $T_{\bf c}$ = 4.4 K. The interpretation of the heat capacity results below $T_{\bf c}$ using the $\alpha-$BCS model unveils the value of $\alpha$ = 2.65, which gives the dimensionless ratio 2$\Delta(0)/k_B T_{\bf c}$ = 5.3, intimating that Sc$_5$Rh$_6$Sn$_{18}$ is a strong-coupling BCS superconductor. The zero-field $\mu$SR measurements in the longitudinal geometry exhibit a signature of a spontaneous appearance of the internal magnetic field below the superconducting transition temperature, indicating that the superconducting state is characterized by the broken time-reversal symmetry (TRS). We have compared the results of broken TRS in Sc$_5$Rh$_6$Sn$_{18}$ with that observed in R$_5$Rh$_6$Sn$_{18}$ (R = Lu and Y).Comment: 6 pages, 4 figures. arXiv admin note: text overlap with arXiv:1411.687

TINGKAH LAKU IKAN CUPANG (Betta splendes) TERHADAP PAKAN YANG BERBEDA

Ikan cupang (Betta splendes) adalah salah satu ikan hias air tawar di daerah tropis (Linke, 1994). Salah satu keistimewaan ikan cupang adalah daya tarik pada warna yang dimunculkan dari tubuhnya seperti bentuk, tampilan dan warnanya (Susanto, 1992). Fungsi utama pakan adalah untuk kelangsunan hidup dan pertumbuhan (Mujiman, 1992). Tingkah laku ikan terhadap pakan secara umum mempunyai dua pola yaitu aktif mencari pakan pada siang hari (diurnal) dan malam hari (nokturnal). Untuk ikan cupang termasuk tipe diurnal (Mudjiman, 2008). Penelitian ini bertujuan untuk mengetahui tingkah laku atau respon ikan cupang (Betta splendes) terhadap pakan yang berbeda dan untuk mengetahui pertumbuhan dan sintasan hidup ikan cupang (Betta splendes). Wadah yang digunakan dalam penelitian adalah toples kaca sebanyak 9 buah. Ikana cupang yang menjadi obyek penelitian sebanyak 9 ekor. Pakan yang diberikan adalah pakan cacing sutra (Tubifex sp), cacing darah, dan pelet “Takari” sebanyak 2 (dua) kali dalam sehari secara “ed libitum”. Respon makan ikan cupang berbeda-beda, dimana pemberian cacing sutra adalah kurangaktif, pakan cacing darah adalah sangat aktif dan pakan Takari adalah aktif. Pertumbuhan panjang rata-rata ikan cupang yang tertinggi pada wadah B (cacing darah) yaitu 3,3 cm dan diikuti wadah C (pakan Takari) yaitu 3,0 cm dan wadah A (cacing sutra) yaitu 2,9 cm. Pertambahan berat rata-rata yang tertinggi pada wadah B (cacing darah) yaitu 1,50gr, sedangkan wadah C (pakan Takari) yaitu 1,20 gr dan wadah A (cacing sutra) yaitu 1,07gr. Tingkat keberhasilan hidup ikan cupang (B.splendes) untuk semua wadah pemeliharaan adalah 100%

Broken time-reversal symmetry probed by muon spin relaxation in the caged type superconductor Lu5Rh6Sn18

The superconducting state of the caged type compound Lu5Rh6Sn18 has been investigated by using magnetization, heat capacity, and muon spin relaxation or rotation (?SR) measurements, and the results interpreted on the basis of the group theoretical classifications of the possible pairing symmetries and a simple model of the resulting quasiparticle spectra. Our zero-field ?SR measurements clearly reveal the spontaneous appearance of an internal magnetic field below the transition temperature, which indicates that the superconducting state in this material is characterized by broken time-reversal symmetry. Further, the analysis of the temperature dependence of the magnetic penetration depth measured using the transverse-field ?SR measurements suggests an isotropic s?wave character for the superconducting gap. This is in agreement with the heat capacity behavior, and we show that it can be interpreted in terms of a nonunitary triplet state with point nodes and an open Fermi surface

Investigation of Superconducting Gap Structure in HfIrSi using muon spin relaxation/rotation

Appearance of strong spin-orbit coupling (SOC) is apparent in ternary equiatomic compounds with 5$d$-electrons due to the large atomic radii of transition metals. SOC plays a significant role in the emergence of unconventional superconductivity. Here we examined the superconducting state of HfIrSi using magnetization, specific heat, zero and transverse-field (ZF/TF) muon spin relaxation/rotation ($\mu$SR) measurements. Superconductivity is observed at $T_\mathrm{C}$ = 3.6 K as revealed by specific heat and magnetization measurements. From the TF$-\mu$SR analysis it is clear that superfluid density well described by an isotropic BCS type $s$-wave gap structure. Furthermore, from TF$-\mu$SR data we have also estimated the superconducting carrier density $n_\mathrm{s}$ = 6.6 $\times$10$^{26}$m$^{-3}$, London penetration depth $\lambda_{L}(0)$ = 259.59 nm and effective mass $m^{*}$ = 1.57 $m_{e}$. Our zero-field muon spin relaxation data indicate no clear sign of spontaneous internal field below $T_\mathrm{C}$, which implies that the time-reversal symmetry is preserved in HfIrSi. Theoretical investigation suggests Hf and Ir atoms hybridize strongly along the $c$-axis of the lattice, which is responsible for the strong three-dimensionality of this system which screens the Coulomb interaction. As a result despite the presence of correlated $d$-electrons in this system, the correlation effect is weakened, promoting electron-phonon coupling to gain importance.Comment: 8 pages, 4 figure

Probing the superconducting ground state of ZrIrSi: A μ\muSR study

The superconducting ground state of newly reported ZrIrSi is probed by means of $\mu$SR technique along with resistivity measurement. The occurrence of superconductivity at $T_\mathrm{C}$ = 1.7 K is confirmed by resistivity measurement. ZF-$\mu$SR study revealed that below $T_\mathrm{C}$, there is no spontaneous magnetic field in the superconducting state, indicates TRS is preserved in case of ZrIrSi. From TF-$\mu$SR measurement, we have estimated the superfluid density as a function of temperature, which is described by an isotropic $s-$wave model with a superconducting gap $2\Delta(0)/k_\mathrm{B}T_\mathrm{C}$ = 5.1, indicates the presence of strong spin-orbit coupling. {\it Ab-initio} electronic structure calculation indicates that there are four bands passing through the Fermi level, forming four Fermi surface pockets. We find that the low-energy bands are dominated by the $4d$-orbitals of transition metal Zr, with substantially lesser weight from the $5d$-orbitals of the Ir-atoms.Comment: 6 pages, 4 figure

Field Theory in Noncommutative Minkowski Superspace

There is much discussion of scenarios where the space-time coordinates x^\mu are noncommutative. The discussion has been extended to include nontrivial anticommutation relations among spinor coordinates in superspace. A number of authors have studied field theoretical consequences of the deformation of N=1 superspace arising from nonanticommutativity of coordinates \theta, while leaving \bar{theta}'s anticommuting. This is possible in Euclidean superspace only. In this note we present a way to extend the discussion by making both \theta and \bar{theta} coordinates non-anticommuting in Minkowski superspace. We present a consistent algebra for the supercoordinates, find a star-product, and give the Wess-Zumino Lagrangian L_{WZ} within our model. It has two extra terms due to non(anti)commutativity. The Lagrangian in Minkowski superspace is always manifestly Hermitian and for L_{WZ} it preserves Lorentz invariance.Comment: 8 pages, added references, two-column format, published in PR