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Challenges of enhancing productivity by amplifying efficiency and man-machine compatibility of equipment can be achieved by adopting advanced technologies. This study aims to present and exemplify methodology for incorporating ergonomics pro-actively into the design using computer-aided design and digital human modeling-based analysis. The cleaning equipment is parametrized to detect the critical variables. The relations are then constrained through the 3DSSPP software-based biomechanical and experimental analysis using a prototype. MATLAB and Minitab software is used for optimizing efficiency while satisfying the established constraints. The experiment showed nearly 67%, 120%, and 241% successive improvement in the mechanical advantage in comparison to their immediate predecessors. A significant (6 point) reduction in rapid entire body assessment score has been observed in the final posture while working with the manipulator. 3DSSPP suggested that the joint forces during the actuation of the manipulator were acceptable to 99% of the working population. The study demonstrated the potential of the methodology in revamping the equipment for improved ergonomic design., Comment: page count: 33; word count (Excluding references and abstract): 5413; abstract word count: 161; number of figures: 11; number of tables: 3

We report the effect of 4f electron doping on structural, electrical and magneto-transport properties of Dy doped half Heusler Y1-x(Dy)xPdBi (x =0, 0.2, 0.5, 1) thin films grown by pulsed laser deposition. The Dy doping leads to lattice contraction which increases from 0% for the parent x =0 sample to approx 1.3% for x=1 sample with increase in Dy doping. The electrical transport measurements show a typical semi-metallic behaviour in the temperature range 3K to 300K and a sharp drop in resistivity at low temperatures (less than 3K) for all the samples. Magnetotransport measurements and Shubnikov de-Hass oscillations at high magnetic fields demonstrate that for these topologically non-trivial samples, Dy doping induced lattice contraction plays an active role in modifying the Fermi surface, carrier concentration and the effective electron mass. There is an uniform suppression of the onset of superconductivity with increased Dy doping which is possibly related to the increasing local exchange field arising from the 4f electrons in Dy. Our results indicate that we can tune various band structure parameters of YPdBi by f electron doping and strained thin films of Y1-x(Dy)xPdBi show surface dominated relativistic carrier transport at low temperatures., Comment: 20 pages, 11 figures

Mesoscopic point contacts between elemental metals and the topological 3D Dirac semimetal Cd$_3$As$_2$ have been recently shown to be superconducting with unconventional pairing while Cd$_3$As$_2$ itself does not superconduct. Here we show that the same superconducting phase at mesoscopic interfaces on Cd$_3$As$_2$ can be induced with a known conventional superconductor Nb where a pronounced zero-bias conductance peak is observed which undergoes splitting in energy under certain conditions. The observations are consistent with the theory of the emergence of Andreev bound states (ABS) due to the presence of a pair potential with broken time reversal symmetry. The data also indicate the possibility of Majorana bound states as expected at the interfaces between $s$-wave superconductors and topologically non-trivial materials with high degree of spin-orbit coupling., Comment: 10 pages, 3figures

From temperature and magnetic field dependent point-contact spectroscopy on the ferromagnetic superconductor Sr$_{0.5}$Ce$_{0.5}$FBiS$_2$ (bulk superconducting $T_c$ = 2.5 K) we observe (a) a pseudogap in the normal state that sustains to a remarkably high temperature of 40 K and (b) two-fold enhancement of $T_c$ upto 5 K in the point-contact geometry. In addition, Andreev reflection spectroscopy reveals a superconducting gap of 6 meV for certain point-contacts suggesting that the mean field $T_c$ of this system could be approximately 40 K, the onset temperature of pseudo-gap. Our results suggest that quantum fluctuations originating from other competing orders in Sr$_{0.5}$Ce$_{0.5}$FBiS$_2$ forbid a global phase coherence at high temperatures thereby suppressing $T_c$. Apart from the known ordering to a ferromagnetic state, our first-principles calculations reveal nesting of a multi-band Fermi surface and a significant electron-phonon coupling that could result in charge density wave-like instabilities., Comment: This is an author-created, un-copyedited version of an article accepted for publication in Journal of Physics: Cond-mat. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it

Neutron scattering studies have been carried out on polycrystalline samples of a series of rare earth intermetallic compounds RCuAs$_2$ (R = Pr, Nd, Dy, Tb, Ho and Yb) as a function of temperature to determine the magnetic structures and the order parameters. These compounds crystallize in the ZrCuSi$_2$ type structure, which is similar to that of the RFeAsO (space group P4/nmm) class of iron-based superconductors. PrCuAs$_2$ develops commensurate magnetic order with K = (0, 0, 0.5) below T$_N$ = 6.4 (2) K, with the ordered moments pointing along the c-axis. The irreducible representation analysis shows either a ${\Gamma}$$^1_2$ or ${\Gamma}$$^1_3$ representation. NdCuAs$_2$ and DyCuAs$_2$ order below T$_N$ = 3.54(5) K and T$_N$ = 10.1(2) K, respectively, with the same ordering wave vector but the moments lying in the a-b plane (with a ${\Gamma}$$^2_9$ or ${\Gamma}$$^2_{10}$ representation). TbCuAs$_2$ and HoCuAs$_2$ exhibit incommensurate magnetic structures below T$_N$ = 9.44(7) and 4.41(2) K, respectively. For TbCuAs$_2$, two separate magnetic ordering wave vectors are established as K$_{1(Tb)}$ = (0.240,0.155,0.48) and K$_{2(Tb)}$ = (0.205, 0.115, 0.28), whereas HoCuAs$_2$ forms a single K$_{(Ho)}$ = (0.121, 0.041, 0.376) magnetic structure with 3$^{rd}$ order harmonic magnetic peaks. YbCuAs$_2$ does not exhibit any magnetic Bragg peaks at 1.5 K, while susceptibility measurements indicate an antiferromagnetic-like transition at 4 K, suggesting that either the ordering is not long range in nature or the ordered moment is below the sensitivity limit of $\approx$ 0.2 $\mu_B$., Comment: 8 figures

Detailed magnetic studies including magneto-caloric measurements on magnetic multiferroic quadruple perovskite CaMn7O12 are presented. Based on the collective response of Arrott plots and {\Delta}SM (T), a magnetic phase diagram of CaMn7O12 is suggested. A new magnetic transition at TN3 ~20 K where the system changes from noncollinear AFM to collinear AFM is reported. An anomaly observed in both {\Delta}SM (T) and Arrott plots around 64 K has been attributed to high external field induced spin canting leading to change in magnetic order inducing phase transition. Magneto-caloric effect in this material is presented for the first time. The peak value of change in isothermal magnetic entropy is 1.3 J/K-Kg and the value of refrigeration capacity is reported to be 34.5 J/Kg for the field of 7 T.

We have carried out detailed magnetic and transport studies of the new Sr0.5Ce0.5FBiS2-xSex (x = 0.5, 1) superconductors derived by doping Se in Sr0.5Ce0.5FBiS2. Se-doping produces several effects: it suppresses semiconducting like behavior observed in the undoped Sr0.5Ce0.5FBiS2, ferromagnetic ordering temperature, TFM, decreases considerably from 7.5 K (in Sr0.5Ce0.5FBiS2) to 3.5 K and superconducting transition temperature, Tc, gets enhanced slightly to 2.9 - 3.3 K. Thus in these Se-doped materials, TFM is just marginally higher than Tc. Magnetization studies provide an evidence of bulk superconductivity in Sr0.5Ce0.5FBiS2-xSex. Quite remarkably, as compared with the effective paramagnetic Ce-moment (~ 2.2 muB), the ferromagnetically ordered Ce-moment in the superconducting state is rather small (~ 0.1 muB). To the best of our knowledge, the title compounds are the first Ce-based superconducting itinerant ferromagnetic materials (Tc < TFM). We stress that Ce-4f electrons are responsible for both superconductivity and ferromagnetism just as U-5f electrons are in UCoGe. Furthermore, a novel feature of these materials is a dual hysteresis loop corresponding to both the ferromagnetism and the coexisting superconductivity. Such features of Sr0.5Ce0.5FBiS2-xSex put these materials apart from the well known U-containing superconducting ferromagnets reported so far., Comment: 12 pages, 5 figures + 4 supplementary figures

We have synthesized a new crystallographically ordered quaternary Heusler alloy, MnNiCuSb. The crystal structure of the alloy has been determined by Rietveld refinement of the powder x-ray diffraction data. This alloy crystallizes in the LiMgPdSb type structure with F-43m space group. MnNiCuSb is a ferromagnet with a high TC ~ 690K and magnetic moment of 3.85MuB/f.u. Besides this we have also studied two other off-stoichiometric compositions; one Cu rich and the other Ni rich (MnNi0.9Cu1.1Sb and MnNi1.1Cu0.9Sb) which are also ferromagnets. It must be stressed that MnNiCuSb is one of the very few known, non-Fe containing quaternary Heusler alloys with 1: 1: 1: 1 composition., Comment: 10 pages, 4 figures

Critical current density (Jc), thermal activation energy (U0), and upper critical field (Hc2) of La1-xSmxO0.5F0.5BiS2 (x = 0.2, 0.8) superconductors are investigated from magnetic field dependent \r{ho}(T) studies. The estimated upper critical field (Hc2) has low values of 1.04 T for x = 0.2 and 1.41 T for x = 0.8. These values are lower than Sm free LaO0.5F0.5BiS2 superconductor (1.9 T). The critical current density (Jc) is estimated to be 1.35*105 A/cm2 and 5.07 *105 A/cm2 (2 K) for x = 0.2 and 0.8 respectively, using the Bean's model. The thermal activation energy (U0/kB) is 61 K for x = 0.2 and 140 K for x =0.8 as calculated from Arrhenius plots at low magnetic field (1 T) and indicates a strong flux pinning potential which might be co-existing with applied magnetic field., Comment: 13 pages, 4 figures

Polycrystalline Eu0.5La0.5BiS2F was synthesized by solid state reaction which crystallizes in the tetragonal CeOBiS2 structure (P4/nmm). We report here enhancement of Tc to 2.2 K in Eu0.5La0.5BiS2F (by electron doping in EuBiS2F with Tc ~ 0.3 K). Eu0.5La0.5BiS2F is semiconducting down to 3 K and an onset of superconductivity is seen at 2.2 K at ambient pressure. Upon application of pressure the Tc could be enhanced upto 10 K. Step like features are seen in the resistivity curves at intermediate pressures (0.5 - 1 GPa) which hints towards the possible existence of two phases with different Tc. At a pressure above 1.38GPa, the Tconset remains invariant at 10 K but the Tc(\r{ho}=0) is increased to above 8.2 K. There is a possible transformation from a low Tc phase to a high Tc phase by application of pressure., Comment: Accepted in Supercond. Sci. Technol. (Sept 2015)

Since the three dimensional (3D) Dirac semi-metal Cd$_3$As$_2$ exists close to topological phase boundaries, in principle it should be possible to drive it into exotic new phases, like topological superconductors, by breaking certain symmetries. Here we show that the mesoscopic point-contacts between silver (Ag) and Cd$_3$As$_2$ exhibit superconductivity up to a critical temperature (onset) of 6 K while neither Cd$_3$As$_2$ nor Ag are superconductors. A gap amplitude of 6.5 meV is measured spectroscopically in this phase that varies weakly with temperature and survives up to a remarkably high temperature of 13 K indicating the presence of a robust normal-state pseudogap. The observations indicate the emergence of a new unconventional superconducting phase that exists only in a quantum mechanically confined region under a point-contact between a Dirac semi-metal and a normal metal., Comment: includes supplementary materials at the end

We have synthesized CuFeAs, a new iron-pnictide compound with a layered tetragonal Cu2Sb type structure (space group P4/nmm: a = b = 3.7442(2) {\AA} and c = 5.8925(4) {\AA}) that is identical to that of 111-type iron-based superconductors. Our measurements suggest that in low applied magnetic field it undergoes an antiferromagnetic transition below TN ~ 9 K. When compared with the ground state of CuFeSb, recently reported 111-type ferromagnetic material (TC ~ 375 K), it has important implication with regard to the nature of Fe-Fe magnetic interaction in Fe-As materials. CuFeAs does not exhibit superconductivity down to 2 K., Comment: 8 pages, 5 figures

Crystal structure and properties of a new member of oxy-bismuth-sulfide SmO1-xFxBiS2 are reported here. The compounds SmO1-xFxBiS2 (x = 0.0 and 0.5) are found to be isostructural with LaOBiS2 and crystallize in the CeOBiS2 type structure (P4/nmm). Sm substitution in LaO0.5F0.5BiS2, (La1-ySmyO0.5F0.5BiS2), leads to a gradual decrease in a-lattice constant however the c-lattice constant does not show such a gradual trend. Enhancement in Tc is achieved upon partially substituting La by smaller Sm ion. Maximum Tc ~ 4.6 K was observed for composition with y = 0.8. Disobeying this trend Tc disappears unexpectedly in composition SmO0.5F0.5BiS2 (y = 1.0). Both the undoped and F-doped (x = 0.0 and 0.5) compounds are paramagnetic exhibiting semiconducting behavior down to 2 K., Comment: Accepted, Inorganic Chemistry (2015)

CuFeSb is isostructural to the ferro-pnictide and chalcogenide superconductors and it is one of the few materials in the family that are known to stabilize in a ferromagnetic ground state. Majority of the members of this family are either superconductors or antiferromagnets. Therefore, CuFeSb may be used as an ideal source of spin polarized current in spin-transport devices involving pnictide and the chalcogenide superconductors. However, for that the Fermi surface of CuFeSb needs to be sufficiently spin polarized. In this paper we report direct measurement of transport spin polarization in CuFeSb by spin-resolved Andreev reflection spectroscopy. From a number of measurements using multiple superconducting tips we found that the intrinsic transport spin polarization in CuFeSb is high ($\sim$ 47\%). In order to understand the unique ground state of CuFeSb and the origin of large spin polarization at the Fermi level, we have evaluated the spin-polarized band structure of CuFeSb through first principles calculations. Apart from supporting the observed 47\% transport spin polarization, such calculations also indicate that the Sb-Fe-Sb angles and the height of Sb from the Fe plane is strikingly different for CuFeSb than the equivalent parameters in other members of the same family thereby explaining the origin of the unique ground state of CuFeSb., Comment: 6 pages, 4 figures

We report inelastic light scattering experiments on superconductor Ce0.6Y0.4FeAsO0.8F0.2 from 4K to 300K covering the superconducting transition temperature Tc ~ 48.6K. A strong evidence of the superconductivity induced phonon renormalization for the A1g phonon mode near 150 cm-1 associated with the Ce/Y vibrations is observed as reflected in the anomalous red-shift and decrease in the linewidth below Tc. Invoking the coupling of this mode with the superconducting gap, the superconducting gap (2) at zero temperature is estimated to be ~ 20 meV i.e the ratio is ~ 5, suggesting Ce0.6Y0.4FeAsO0.8F0.2 to belong to the class of strong coupling superconductors. In addition, the mode near 430 cm-1 associated with Ce3+ crystal field excitation also shows anomalous increase in its linewidth below Tc suggesting strong coupling between crystal field excitation and the superconducting quasi-particles. Our observations of two high frequency modes (S9 and S10) evidence the non-degenerate nature of Fe2+ dxz/yz orbitals suggesting the electronic nematicity in these systems., Comment: Accepted for 58th DAE-SSPS 2013

We have systematically studied the substitution of nonmagnetic Zn and magnetic Ni at iron sites in Ce based oxypnictide. The parent compound (CeOFeAs) shows an anomaly in resistivity around 150 K due to structural transition from tetragonal (space group: P4/nmm) to orthorhombic structure (space group: Cmma). Substitution of Zn suppresses this anomaly to lower temperature (~130 K) but Ni substitution does not show any anomaly around this temperature and the compound behaves like a metal. Further, we find that non magnetic (Zn) doping leads to higher impurity scattering as compared to magnetic Ni doping. Similar to the resistivity measurement, the specific heat shows another jump near 4 K for CeOFeAs. This is attributed to the ordering of Ce3+ moments. This peak shifts to 3.8 K for Zn substituted compound and there is no change in the ordering temperature in the Ni substituted CeOFeAs. These peaks are broadened in applied magnetic field (5 T) and the calculated magnetic entropy tends to saturate at the same value for 0 T and 5 T external magnetic field., Comment: 16 pages Text+Figs

We report temperature-dependent Raman spectra of CeFeAsO0.9F0.1 from 4 K to 300 K in spectral range of 60 to 1800 cm-1 and interpret them using estimates of phonon frequencies obtained from first-principles density functional calculations. We find evidence for a strong coupling between the phonons and crystal field excitations; in particular Ce3+ crystal field excitation at 432 cm-1 couples strongly with Eg oxygen vibration at 389 cm-1 . Below the superconducting transition temperature, the phonon mode near 280 cm-1 shows softening, signaling its coupling with the superconducting gap. The ratio of the superconducting gap to Tc thus estimated to be ~ 10 suggests CeFeAsO0.9F0.1 as a strong coupling superconductor. In addition, two high frequency modes observed at 1342 cm-1 and 1600 cm-1

PrOFe0.9Co0.1As is known to be a superconductor with a TC of ~14 K. In an attempt to induce charge transfer and also induce chemical pressure between the FeAs and PrO layers we have synthesized for the first time oxypnictides of the type PrOFe0.9Co0.1As1-xPx (P doping at As sites). All the compounds crystallize in the tetragonal ZrCuSiAs type structure (space group = P4/nmm). The lattice parameters (a and c) decrease as expected on substitution of smaller phosphorous at the arsenic site in PrOFe0.9Co0.1As and a decrease in TC was observed on substitution of P ions at a low rate of 0.13K/at. % of P for x > 0.1. The irreversibility field (Hirr) and critical current density (JC), obtained using the AC susceptibility measurements was found to decrease monotonically with increasing 'P' concentration. 'Hirr' is observed to be much smaller than HC2, pointing to a very low pinning energy. The pinning potential obtained using both in-field transport and AC susceptibility measurements indicate a low value of ~40 meV and show no significant variation with P substitution., Comment: 17 pages, 8 figures (accepted); Superconductor Science and Technology (2011)

We report interesting anomalies in the temperature dependent Raman spectra of FeSe$_{0.82}$ measured from 3K to 300K in the spectral range from 60 to 1800 cm$^{-1}$ and determine their origin using complementary first-principles density functional calculations. A phonon mode near 100 cm$^{-1}$ exhibits a sharp increase by $\sim$ 5% in frequency below a temperature T$_s$ ($\sim$ 100 K) attributed to strong spin-phonon coupling and onset of short-range antiferromagnetic order. In addition, two high frequency modes are observed at 1350 cm$^{-1}$ and 1600 cm$^{-1}$, attributed to electronic Raman scattering from ($x^2-y^2$)to $xz$ / $yz$ $d$-orbitals of Fe., Comment: 19 pages, 4 figures, 1 table

We report significant enhancement in superconducting properties of yttrium substituted Ce1-xYxOFFeAs superconductors. The polycrystalline samples were prepared by two step solid state reaction technique. X-ray diffraction confirmed tetragonal ZrCuSiAs structure with decrease in both a and c lattice parameters on increasing yttrium substitution (with fixed F content). With smaller ion Y in place of Ce, the transition temperature increased by 6 K. Yttrium doping also lead to higher critical fields as well as stronger inter and intra-granular current density. The magnetization critical current density increased by an order of magnitude at 30 K and 1 T magnetic field., Comment: 14 pages, 4 figures

Electron-doping of the semimetal (CeOFeAs) by either fluorine (max Tc ~ 43 K)or cobalt (max Tc ~ 11 K) leads to superconductivity. Here we show the effect of transition metal (Co) substitution at the iron site on the superconducting properties of CeO0.9F0.1FeAs (Tc ~38 K)to understand the interplay of charge carriers in both the rare earth-oxygen and Fe-As layers. Simultaneous doping of equivalent number of charge carriers in both layers leads to a Tc of 9.8 K which is lower than the Tc obtained when either the conducting layer (CeAs) or charge reservoir layer (CeO) is individually doped. This suggests a clear interplay between the two layers to control the superconductivity. The resistivity shows a T2 dependence (T >>Tc) which indicates strong electron-electron correlation. Hall coefficient and thermoelectric power indicate increased carrier concentration with cobalt doping in CeO0.9F0.1FeAs. The rf penetration depth both for CeO0.9F0.1Fe0.95Co0.05As and CeO0.9F0.1FeAs show an exponential temperature dependence with a gap value of ~ 1.6 and 1.9 meV. A resistance minimum is observed in the normal state near Tc which also shows negative magnetoresistance and provides evidence for the onset of weak localization.

We report the synthesis and characterization of a new electron-doped La-oxypnictide superconductor by partial substitution of lanthanum by thorium. The superconducting transition temperature at about 30.3 K was observed in La0.8Th0.2OFeAs which is the highest in La-based oxypnictide superconductors synthesized at ambient pressure. We find that the decrease in lattice parameters with Th doping in LaOFeAs is more drastic as compared to that obtained by high pressure (6 GPa) synthesis of oxygen deficient LaOFeAs. The resistivity and magnetic susceptibility measurements yield an upper critical field Hc2 (0) of 47 T. Partial substitution of Th in place of La induces electron doping as evidenced by negative Seebeck coefficient. The temperature dependent magnetic penetration depth data provides strong evidence for a nodeless low energy gap of 1.4 meV.