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The interplay of nontrivial topology and superconductivity in condensed matter physics gives rise to exotic phenomena. However, materials are extremely rare where it is possible to explore the full details of the superconducting pairing. Here, we investigate the momentum dependence of the superconducting gap distribution in a novel Dirac material PdTe. Using high resolution, low temperature photoemission spectroscopy, we establish it as a spin-orbit coupled Dirac semimetal with the topological Fermi arc crossing the Fermi level on the (010) surface. This spin-textured surface state exhibits a fully gapped superconducting Cooper pairing structure below Tc~4.5K. Moreover, we find a node in the bulk near the Brillouin zone boundary, away from the topological Fermi arc.These observations not only demonstrate the band resolved electronic correlation between topological Fermi arc states and the way it induces Cooper pairing in PdTe, but also provide a rare case where surface and bulk states host a coexistence of nodeless and nodal gap structures enforced by spin-orbit coupling., Comment: accepted by PRL

This study addresses a perennial problem in the synthesis of copper vanadates, namely, that of phase purity. A time-efficient solution combustion synthesis (SCS) was employed for obtaining α-CuV2O6...

While exploring novel magnetic semiconductors, the new phase Cr0.65Al1.35Se3 was discovered and characterized by both structural and physical properties. Cr0.65Al1.35Se3 was found to crystallize into orthorhombic CrGeTe3-type structure with space group Pnma (no. 62). Vacancies and mixed occupancies were tested, and the results show that one of the 4c sites accommodates a mixture of Cr and Al atoms, while the other 4c site is fully occupied by Al atoms. Unique structural features include a T-shaped channel network created from the edge-sharing Cr/Al@Se6 and Al@Se4 polyhedra and a zipper effect of the puckered Se atoms inside the columnar channels. The round peak observed in the temperature-dependent magnetic susceptibility (χg) plot at ∼8(1) K corresponds to the antiferromagnetic-type transition in Cr0.65Al1.35Se3. However, the positive θCW indicates an additional ferromagnetic interaction, which is highly likely due to the complex magnetic structure arising from the mixed Cr/Al occupancies on the 4c site. Electrical resistivity measurements confirm that Cr0.65Al1.35Se3 is a semimetal with a positive magnetoresistance. Here we present the characterization and determination of the crystal structure and physical properties for this new material.

We report the experimental and theoretical investigation of structure, chemical bonding interactions, and physical properties of new ternary stannides AIrSn2 (A = Sr and Ba). AIrSn2 (A = Sr and Ba) crystallizes in the orthorhombic Re3B-type structure with the space group Cmcm (No. 64). According to single-crystal X-ray diffraction results, the structure of AIrSn2 (A = Sr and Ba) can be considered as a Zintl-type compound with heterogeneous polyanionic [IrSn2]2− and A2+. The specific heat down to 1.8 K shows no evidence for bulk superconductivity in either SrIrSn2 or BaIrSn2. Electronic structure calculations, especially chemical bonding interactions in SrIrSn2 and BaIrSn2, match well with the observed structural stability and metallic nature.

A novel antiferromagnetic semiconductor, Eu3Sn2P4, has been discovered. Single crystals of Eu3Sn2P4 were prepared using the Sn self-flux method. The crystal structure determined by single crystal X-ray diffraction shows that Eu3Sn2P4 crystallizes in the orthorhombic structure with the space group Cmca (Pearson Symbol, oP216). Six Sn–Sn dimers connected by P atoms form a Sn12P24 crown-shaped cluster with a Eu atom located in the center. Magnetization measurements indicate that the system orders antiferromagnetically below a TN ∼14 K at a low field and undergoes a metamagnetic transition at a high field when T < TN. The effective magnetic moment is 7.41(3) μB per Eu, corresponding to Eu2+. The electric resistivity reveals a non-monotonic temperature dependence with non-metallic behavior below ∼60 K, consistent with the band structure calculations. By fitting the data using the thermally activated resistivity formula, we estimate the energy gap to be ∼0.14 eV. Below TN, the resistivity tends to saturate, suggesting the reduction of charge-spin scattering.

Magnetic structure and crystal symmetry, which primarily determine the time-reversal and inversion symmetry, may give rise to numerous exotic quantum phenomena in magnetic semiconductors and semimetals when arranged in different patterns. In this work, a new layered magnetic semiconductor, Eu3−δZn xSn yAs3, was discovered and high-quality single crystals were grown using the Sn flux. According to structural characterization by x-ray diffraction and atomic-resolution scanning transmission electron microscopy, Eu3−δZn xSn yAs3 is found to crystallize in a hexagonal symmetry with the space group P63/ mmc (No. 194). After examining different specimens, we conclude that their stoichiometry is fixed at ∼Eu2.6Zn0.65Sn0.85As3, which meets the chemical charge balance. Eu3−δZn xSn yAs3 is composed of septuple (Eu1−δSn yAs2)-Eu-(Zn xAs)-Eu sequences. The shortest Eu–Eu distance in the system is between two Eu layers separated by Zn xAs along the c-axis. Magnetization measurement shows an antiferromagnetic ordering in Eu3−δZn xSn yAs3 at TN ∼ 12 K, where the magnetic easy-axis is along the c-axis, and Mössbauer spectroscopy observes magnetic hyperfine splitting on Eu and Sn at 6 K. Magnetic anisotropy is significantly different from the ones along the ab-plane in other layered Eu-based magnetic semimetals. Heat capacity measurements confirm the magnetic transition around 12 K. Electrical resistivity measurement indicates semiconductor behavior with a band gap of ∼0.86 eV. Various Eu-based magnetic semiconductors could provide a tunable platform to study potential topological and magnetic properties.

Comprehensive analyses of the 115In-NQR spectra employing a magnetic dipolar model and a transferred hyperfine model are performed to determine the magnetic structures of Ce3PtIn11. Based on this analysis, we confirmed that the magnetic moment at the Ce(1) site is very small (∼ 4% of that at the Ce(2) site) but finite. Further, for T N2 < T < T N1 and T < T N2, the magnetic moments at the Ce(1) and Ce(2) sites are parallel to the c-axis, and the in-plane propagation vectors in the two Ce atoms sublattices are (qa, qb ) = (1/2, 1/2). In the temperature interval T N2

Nuclear quadrupole resonance (NQR) measurements were performed on the heavy-fermion superconductor ${\mathrm{Ce}}_{3}{\mathrm{PtIn}}_{11}$ with ${T}_{\mathrm{c}}=0.32\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. The temperature dependence of both spin-lattice relaxation rate $1/{T}_{1}$ and NQR spectra evidences the occurrence of two successive magnetic transitions with ${T}_{\mathrm{N}1}\ensuremath{\simeq}2.2\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ and ${T}_{\mathrm{N}2}\ensuremath{\simeq}2.0\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. In successive magnetic transitions, even though the magnetic moment at the Ce(2) site plays a major role, the magnetic moment at the Ce(1) site also contributes to some extent. While a commensurate antiferromagnetic ordered state appears for ${T}_{\mathrm{N}2}lTl{T}_{\mathrm{N}1}$, a partially incommensurate antiferromagnetic ordered state is suggested for $Tl{T}_{\mathrm{N}2}$.

Transition metal stannides are usually semiconductors with a narrow band gap. We report experimental investigation on metallic Ir

We report the observation of superconductivity in single-crystalline ${\mathrm{CaPd}}_{2}{\mathrm{P}}_{2}$ and ${\mathrm{SrPd}}_{2}{\mathrm{P}}_{2}$ obtained from Bi-flux. Both ${\mathrm{CaPd}}_{2}{\mathrm{P}}_{2}$ and ${\mathrm{SrPd}}_{2}{\mathrm{P}}_{2}$ crystallize in the ${\mathrm{ThCr}}_{2}{\mathrm{Si}}_{2}$-type structure (space group I4/mmm) with a short P-P distance. Electrical resistivity and specific heat measurements conjointly corroborate bulk superconductivity at ${T}_{c}\ensuremath{\sim}1.0$ K with $\mathrm{\ensuremath{\Delta}}C/\ensuremath{\gamma}{T}_{\mathrm{c}}=1.42$ for ${\mathrm{CaPd}}_{2}{\mathrm{P}}_{2}$, and ${T}_{c}\ensuremath{\sim}0.7$ K with $\mathrm{\ensuremath{\Delta}}C/\ensuremath{\gamma}{T}_{c}=1.47$ for ${\mathrm{SrPd}}_{2}{\mathrm{P}}_{2}$. The electronic structure calculations and chemical bonding analysis indicate that Pd-P antibonding interactions primarily dominate around the Fermi level and play the critical role in inducing superconductivity.

The crystal structure and elementary properties of La15NbxGe9 are reported. Single-crystal X-ray diffraction, from a crystallite with only 0.12 Nb/formula unit, reveals that this compound, although transition metal deficient, crystallizes in a hexagonal “15-1-9”-like structure type, space group P63mc (no. 186) with lattice parameters a = b = 15.5017(2) A, c = 6.9173(2) A. The physical properties were examined by specific heat and resistivity measurements. La15Nb0.4Ge9 shows metallic behavior, and no superconductivity is observed above 0.4 K. The Sommerfeld coefficient (γ = 62.41(8) mJ mol−1 K−2) and the Debye temperature ( θ D = 267(1) K) were estimated from a fit to the low temperature heat capacity data. La15Nb0.4Ge9 is the first reported compound in the ternary La-Nb-Ge system.

Single crystals of a novel ternary cerium indide CePtIn 4 were grown by self-flux method and studied by means of X-ray diffraction, magnetic susceptibility, heat capacity and electrical resistivity measurements, carried out in wide ranges of temperature and magnetic field strength. The compound was found to crystallize with an orthorhombic crystal structure of the YNiAl 4 -type. It exhibits metallic conductivity and Curie-Weiss paramagnetism due to Ce 3+ ions with well localized 4 f -electrons. At T N = 1.65 K, CePtIn 4 orders antiferromagnetically, possibly with a non-trivial magnetic structure. No superconductivity emerges down to 50 mK. Remarkably, the observed thermodynamic and electrical transport behavior in this compound does not give any hint at strong electronic correlations, typical for cerium intermetallics.

While exploring novel magnetic semiconductors, the new phase Cr

We report on the synthesis of polycrystalline samples of heavy-fermion compound Ce3PtIn11 and the characterization of their structural and low-temperature physical properties. In good agreement with the data previously obtained for single crystals, the polycrystals also form with a tetragonal crystal structure (space group P4/mmm, Z = 1) with the lattice parameters a = b = 4.6934(7) A, and c = 16.8306(3) A. Alike the single crystals, they exhibit two successive antiferromagnetic phase transitions at TN1 = 2.16 K and TN2 = 2.0 K, followed by a superconducting transition at Tc = 0.33 K. Our findings open new opportunities for comprehensive investigations of the interplay between magnetism and superconductivity in Ce3PtIn11 by means of experimental techniques which usually require bulky specimens.

Transition metal stannides are usually semiconductors with a narrow band gap. We report experimental investigation on metallic Ir3Sn7–x Mn x (x = 0 and 0.56). Single crystal x-ray diffraction refinement indicates that Ir3Sn7–x Mn x crystals form a cubic structure (space group Im 3 ̄ m) with the lattice parameter a = 9.362(4) Å for x = 0 and 9.328(6) Å for x = 0.56. The electrical resistivity shows metallic behavior between 2 K and 300 K with T 2 dependence at T < 30 K for x = 0, reflecting the Fermi-liquid ground state. While Ir3Sn7 exhibits weak diamagnetism, partial substitution of Sn by Mn results in spin glass behavior in Ir3Sn7−x Mn x below T g ∼ 13 K for x = 0.56. Remarkably, an upturn in the resistivity is observed in x = 0.56 below ∼2T g, suggesting strong spin fluctuation. This fluctuation is suppressed by the application of magnetic field, which is reflected in the observation of negative magnetoresistance. The unusual properties that emerge due to Mn doping are discussed.

We report the discovery of two new compounds AePd1-xP1+x (Ae = Ca, Sr) crystallized in different hexagonal structures. Single crystals of AePd1-xP1+x (Ae = Ca, Sr) are obtained using the Bi-flux method. Crystallographic analysis by both powder and single crystal X-ray diffraction shows that CaPd1-xP1+x crystallizes in a non-centrosymmetric hexagonal structure with the space group P-6m2 (No.187) and lattice parameters a = b = 4.0391(9) A and c = 4.1026(9) A, while SrPd1-xP1+x forms a centrosymmetric hexagonal structure with the space group P63/mmc (No. 194) and lattice parameters a = b = 4.102(2) A and c = 8.713(4) A. In both compounds, Pd and P atoms mix in the honeycomb layer with a higher amount of P. The electronic structure calculations show that the mixture of Pd and P atoms in the honeycomb network is critical to stabilize the crystal structures. AePd1-xP1+x (Ae = Ca, Sr) are diamagnetic metals confirmed by the magnetic susceptibility, electrical resistivity and specific heat.