Journal Article•
Phase separation at the dimer-superconductor transition in Ir 1−x Rh x Te 2
TL;DR: In this paper, high-energy x-rays in a layered iridium ditelluride superconductor were used to investigate the coexistence of superconductivity and nanoscale dimerization close to the phase boundary.
Abstract: Unconventional superconductivity often appears in proximity of symmetry-breaking electronic and magnetic orders. The relevance of spatiotemporal fluctuations of these orders for the superconducting pairing remains an open question. Here, nanoscale broken-symmetry states are probed by high-energy x-rays in a layered iridium ditelluride superconductor, where superconductivity emerges from an ordered dimer state. The study finds no fingerprints of dimer fluctuations in the superconducting compositional regime, yet provides evidence for the coexistence of superconductivity and nanoscale dimerization close to the phase boundary of these two electronic states.
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TL;DR: In this paper, it was shown that the breaking of Ir-Ir bonds that occurs in Ir1-xPtxTe2 results in the appearance of a structural critical point in the T = 0 limit at xc = 0.035.
Abstract: IrTe2, a layered compound with a triangular iridium lattice, exhibits a structural phase transition at approximately 250 K. This transition is characterized by the formation of Ir-Ir bonds along the b-axis. We found that the breaking of Ir-Ir bonds that occurs in Ir1-xPtxTe2 results in the appearance of a structural critical point in the T = 0 limit at xc = 0.035. Although both IrTe2 and PtTe2 are paramagnetic metals, superconductivity at Tc = 3.1 K is induced by the bond breaking in a narrow range of x > xc in Ir1-xPtxTe2. This result indicates that structural fluctuations can be involved in the emergence of superconductivity.
88 citations
Journal Article•
TL;DR: Guguchia et al. as discussed by the authors investigated the temperature-dependent magnetic penetration depth in Td-MoTe2 under pressure, suggesting a topologically nontrivial s+− order parameter.
Abstract: In its orthorhombic Td polymorph, MoTe2 is a type-II Weyl semimetal, where the Weyl fermions emerge at the boundary between electron and hole pockets. Non-saturating magnetoresistance and superconductivity were also observed in Td-MoTe2. Understanding the superconductivity in Td-MoTe2, which was proposed to be topologically non-trivial, is of eminent interest. Here, we report high-pressure muon-spin rotation experiments probing the temperature-dependent magnetic penetration depth in Td-MoTe2. A substantial increase of the superfluid density and a linear scaling with the superconducting critical temperature Tc is observed under pressure. Moreover, the superconducting order parameter in Td-MoTe2 is determined to have 2-gap s-wave symmetry. We also exclude time-reversal symmetry breaking in the superconducting state with zero-field μSR experiments. Considering the strong suppression of Tc in MoTe2 by disorder, we suggest that topologically non-trivial s+− state is more likely to be realized in MoTe2 than the topologically trivial s++ state.Understanding the superconductivity in topological materials is of eminent interest. Here, Guguchia et al. report temperature-dependent magnetic penetration depth in the superconducting state of Td-MoTe2 under pressure, suggesting a topologically nontrivial s+− order parameter.
67 citations
Journal Article•
TL;DR: Jixia Dai et al. as discussed by the authors proposed a method for the extraction of emergent materials from Pohang University of Science and Technology (Pohang 790-784, Korea).
Abstract: Jixia Dai,1,2 Kristjan Haule,1 J. J. Yang,3 Y. S. Oh,1,2 S-W. Cheong,1,2,3 and Weida Wu1,2,* 1Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA 2Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, USA 3Laboratory for Pohang Emergent Materials and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea (Received 18 August 2014; published 11 December 2014)
17 citations
Journal Article•
TL;DR: In this paper, a de Haas-van Alphen (dHvA) oscillation study on IrTe2 single crystals showing complex dimer formations was performed and an intriguing quasi-two-dimensional conducting plane across the layers is induced by dimerization in both cases.
Abstract: We report a de Haas-van Alphen (dHvA) oscillation study on IrTe2 single crystals showing complex dimer formations. By comparing the angle dependence of dHvA oscillations with band structure calculations, we show distinct Fermi surface reconstruction induced by a 1/5-type and a 1/8-type dimerizations. This verifies that an intriguing quasi-two-dimensional conducting plane across the layers is induced by dimerization in both cases. A phase transition to the 1/8 phase with higher dimer density reveals that local instabilities associated with intra- and interdimer couplings are the main driving force for complex dimer formations in IrTe2.
12 citations
TL;DR: In this article, a systematic investigation on the evolution of the structural and physical properties, including the charge density wave (CDW) and superconductivity of the polycrystalline CuIr2Te4−x I x for 0.0 ≤ x ≤ 1.0.
Abstract: We report a systematic investigation on the evolution of the structural and physical properties, including the charge density wave (CDW) and superconductivity of the polycrystalline CuIr2Te4−x I x for 0.0 ≤ x ≤ 1.0. X-ray diffraction results indicate that both of a and c lattice parameters increase linearly when 0.0 ≤ x ≤ 1.0. The resistivity measurements indicate that the CDW is destabilized with slight x but reappears at x ≥ 0.9 with very high T CDW. Meanwhile, the superconducting transition temperature T c enhances as x increases and reaches a maximum value of around 2.95 K for the optimal composition CuIr2Te1.9I0.1 followed by a slight decrease with higher iodine doping content. The specific heat jump (ΔC/γT c) for the optimal composition CuIr2Te3.9I0.1 is approximately 1.46, which is close to the Bardeen–Cooper–Schrieffer value of 1.43, indicating that it is a bulk superconductor. The results of thermodynamic heat capacity measurements under different magnetic fields [C p(T, H)], magnetization M(T, H) and magneto-transport ρ(T, H) measurements further suggest that CuIr2Te4−x I x bulks are type-II superconductors. Finally, an electronic phase diagram for this CuIr2Te4−x I x system has been constructed. The present study provides a suitable material platform for further investigation of the interplay of the CDW and superconductivity.
11 citations
References
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TL;DR: Calibration methods and software have been developed for single crystal diffraction experiments, using both approaches for calibrate, and apply corrections, to obtain accurate angle and intensity information.
Abstract: Detector systems introduce distortions into acquired data. To obtain accurate angle and intensity information, it is necessary to calibrate, and apply corrections. Intensity non-linearity, spatial distortion, and non-uniformity of intensity response, are the primary considerations. It is better to account for the distortions within scientific analysis software, but often it is more practical to correct the distortions to produce ‘idealised’ data. Calibration methods and software have been developed for single crystal diffraction experiments, using both approaches. For powder diffraction experiments the additional task of converting a two-dimensional image to a one-dimensional spectrum is used to allow Rietveld analysis. This task may be combined with distortion correction to produce intensity information and error estimates. High-pressure experiments can introduce additional complications and place new demands on software. Flexibility is needed to be able to integrate different angular regions se...
4,426 citations
2,966 citations
TL;DR: In this article, the authors examined the possibility that this effect is related to dynamical two-dimensional spin correlations, incommensurate with the crystal lattice, that have been observed in La2-SrxCuO4 by neutron scattering.
Abstract: ONE of the long-standing mysteries associated with the high-temperature copper oxide superconductors concerns the anomalous suppression1 of superconductivity in La2-xBaxCuO4 (and certain related compounds) when the hole concentration x is near . Here we examine the possibility that this effect is related to dynamical two-dimensional spin correlations, incommensurate with the crystal lattice, that have been observed in La2-xSrxCuO4 by neutron scattering2–4. A possible explanation for the incommensurability involves a coupled, dynamical modulation of spin and charge in which antiferromagnetic 'stripes' of copper spins are separated by periodically spaced domain walls to which the holes segregate5–9. An ordered stripe phase of this type has recently been observed in hole-doped La2NiO4 (refs 10–12). We present evidence from neutron diffraction that in the copper oxide material La1.6-xNd0.4SrxCuO4, with x = 0.12, a static analogue of the dynamical stripe phase is present, and is associated with an anomalous suppression of superconductivity13,14. Our results thus provide an explanation of the '
' conundrum, and also support the suggestion15 that spatial modulations of spin and charge density are related to superconductivity in the copper oxides.
2,449 citations
TL;DR: In this paper, it was shown that charge-density waves and their concomitant periodic structural distortions occur in all the 4d1/5d1 dichalcogenides and related the observed periodicities of these CDW states to the theoretical form of the parent Fermi surfaces.
Abstract: The d1 layer metals TaS2, TaSe2, NbSe2, in all their various polytypic modifications, acquire, below some appropriate temperature, phase conditions that their electromagnetic properties have previously revealed as ‘anomalous’. Our present electron-microscope studies indicate that this anomalous behaviour usually includes the adoption, at some stage, of a superlattice. The size of superlattice adopted often is forecast in the pattern of satellite spotting and strong diffuse scattering found above the transition. Our conclusions are that charge-density waves and their concomitant periodic structural distortions occur in all these 4d1/5d1 dichalcogenides. We have related the observed periodicities of these CDW states to the theoretical form of the parent Fermi surfaces. Particularly for the 1T octahedrally coordinated polytypes the Fermi surface is very simple and markedly two-dimensional in character, with large near-parallel walls. Such a situation is known theoretically to favour the formation of...
1,648 citations
TL;DR: PDFfit2 is a program as well as a library for real-space refinement of crystal structures capable of fitting a theoretical three-dimensional structure to atomic pair distribution function data and is ideal for nanoscale investigations.
Abstract: PDFfit2 is a program as well as a library for real-space refinement of crystal structures. It is capable of fitting a theoretical three-dimensional (3D) structure to atomic pair distribution function data and is ideal for nanoscale investigations. The fit system accounts for lattice constants, atomic positions and anisotropic atomic displacement parameters, correlated atomic motion, and experimental factors that may affect the data. The atomic positions and thermal coefficients can be constrained to follow the symmetry requirements of an arbitrary space group. The PDFfit2 engine is written in C++ and is accessible via Python, allowing it to inter-operate with other Python programs. PDFgui is a graphical interface built on the PDFfit2 engine. PDFgui organizes fits and simplifies many data analysis tasks, such as configuring and plotting multiple fits. PDFfit2 and PDFgui are freely available via the Internet.
1,483 citations