A topological superconductor (TSC) is characterized by the topologically protected gapless surface state that essentially an Andreev bound consisting of Majorana fermions. While a TSC has not yet been discovered, doped insulator ${\mathrm{Cu}}_{x}{\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$, which superconducts below $\ensuremath{\sim}3\text{ }\text{ }\mathrm{K}$, predicted to possess superconducting state. We report point-contact spectra on cleaved...

Magnetic skyrmion textures are realized mainly in non-centrosymmetric, e.g. chiral or polar, magnets. Extending the field to centrosymmetric bulk materials is a rewarding challenge, where released helicity / vorticity degree of freedom and higher density result intriguing new properties enhanced functionality. We report here on experimental observation lattice (SkL) phase with large topological Hall effect an incommensurate helical pitch as small 2.8 nm metallic Gd3Ru4Al12, which...

The superconductivity recently found in the doped topological insulator Cu(x)Bi₂Se₃ offers a great opportunity to search for superconductor. We have successfully prepared single-crystal sample with large shielding fraction and measured specific-heat anomaly associated superconductivity. temperature dependence of specific heat suggests fully gapped, strong-coupling superconducting state, but BCS theory is not full agreement data, which hints at possible unconventional pairing Cu(x)Bi₂Se₃....

We present measurements of the magnetic susceptibility and thermal expansion a ${\mathrm{LaCoO}}_{3}$ single crystal. Both quantities show strongly anomalous temperature dependence. Our data are consistently described in terms spin-state transition ${\mathrm{Co}}^{3+}$ ions with increasing from low-spin ground state ${(t}_{2g}^{6}{e}_{g}^{0})$ to an intermediate-spin ${(t}_{2g}^{5}{e}_{g}^{1})$ without (100--500 K) $(>500 \mathrm{K})$ orbital degeneracy. attribute lack degeneracy up 500 K...

We present an investigation of the influence structural distortions in charge-carrier doped ${\mathrm{La}}_{1\ensuremath{-}x}{M}_{x}{\mathrm{CoO}}_{3}$ by substituting ${\mathrm{La}}^{3+}$ with alkaline-earth metals strongly different ionic sizes, that is, $M={\mathrm{Ca}}^{2+},$ ${\mathrm{Sr}}^{2+},$ and ${\mathrm{Ba}}^{2+},$ respectively. find both magnetic properties resistivity change nonmonotonically as a function size M. Doping $M={\mathrm{Sr}}^{2+}$ yields higher transition...

We have performed spin- and angle-resolved photoemission spectroscopy of Bi2Te3 present the first direct evidence for existence out-of-plane spin component on surface state a topological insulator. found that magnitude polarization hexagonally deformed Fermi (FS) reaches maximally 25% in-plane counterpart while such sizable does not exist in more circular FS TlBiSe2, indicating hexagonal deformation is responsible deviation from ideal helical texture. The observed much smaller than expected...

A well known semiconductor Cd3As2 has reentered the spotlight due to its unique electronic structure and quantum transport phenomena as a topological Dirac semimetal. For elucidating controlling state, high-quality thin films have been highly desired. Here we report development of an elaborate growth technique high-crystallinity high-mobility with controlled thicknesses observation Hall effect dependent on film thickness. With decreasing thickness 10 nm, states exhibit variations such change...

The superconductor Sn_{1-x}In_{x}Te is a doped topological crystalline insulator and has become important as candidate superconductor, but its superconducting phase diagram poorly understood. By measuring about 50 samples of high-quality, vapor-grown single crystals, we found that the dependence transition temperature Tc on In content x presents qualitative change across critical doping xc ~ 3.8%, at which structural takes place. Intriguingly, in ferroelectric rhombohedral below doping, to...

The superconducting Cu_xBi_2Se_3 is an electron-doped topological insulator and a prime candidate of the superconductor which still awaits discovery. electrochemical intercalation technique for synthesizing Cu_xBi2Se3 offers good control restricting Cu into van-der-Waals gap yields samples with shielding fractions up to ~50%. We report essential details this synthesis present established phase diagram T_c vs x, along fraction x. Intriguingly, those diagrams suggest that there tendency...

We present a study of the structure, electric resistivity, magnetic susceptibility, and thermal expansion ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Eu}}_{x}\mathrm{Co}{\mathrm{O}}_{3}$. $\mathrm{La}\mathrm{Co}{\mathrm{O}}_{3}$ shows temperature-induced spin-state transition around $100\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ metal-insulator $500\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Partial substitution ${\mathrm{La}}^{3+}$ by smaller ${\mathrm{Eu}}^{3+}$ causes chemical pressure leads to...

A detailed analysis of the crystal structure in RETiO3 with RE = La, Nd, Sm, Gd, and Y reveals an intrinsic coupling between orbital degrees freedom lattice which cannot be fully attributed to structural deformation arising from bond-length mismatch. The TiO6 octahedra this series are all irregular shape distortion depending on ionic radius. These octahedron distortions vary more strongly temperature than tilt rotation angles. Around Ti magnetic ordering compounds exhibit strong anomalies...

For the skyrmion-hosting intermetallic ${\mathrm{Gd}}_{2}{\mathrm{PdSi}}_{3}$ with centrosymmetric hexagonal lattice and triangular net of rare earth sites, we report a thorough investigation magnetic phase diagram. Our work reveals an isotropic value critical field for all orientations, where ordering vector $\mathbf{q}$ is depinned from its preferred directions in basal plane. The bulk nature skyrmion other phases was evidenced by specific-heat measurements. Resistivity anisotropy, likely...

We present a study of the thermal conductivity k and thermopower S single crystals La_{1-x}Sr_xCoO_3 with 0<= x <= 0.3. For all Sr concentrations has rather low values, whereas strongly changes as function x. discuss influence temperature- doping-induced spin-state transitions Co ions on both, k. From S, k, electrical resistivity rho we derive thermoelectric figure merit Z=S^2/(k*rho). intermediate find notably large values Z indicating that Co-based materials could be promising candidates...

We report superconductivity in heavily boron-doped bulk silicon carbide related to the diamond structure. The compound exhibits zero resistivity and diamagnetic susceptibility below a critical temperature T c of ∼1.4 K, an effective boron doping concentration higher than 10 21 cm -3 . present H – phase diagram this new superconducting determined from AC susceptibility. In finite DC magnetic fields clear hysteresis was observed between cooling subsequent warming runs. This indicates, contrast...

Quasiparticle dynamics on the topological surface state of Bi2Se3, Bi2Te3, and superconducting CuxBi2Se3 are studied by 7 eV laser-based angle resolved photoemission spectroscopy. We find strong mode-couplings in Dirac-cone states at energies ~3 ~15-20 meV, which leads to an exceptionally large coupling constant ~3, is one strongest ever reported for any material. This result compatible with recent observation a Kohn anomaly phonon dispersion but it appears that theoretically proposed...

Electronic structure of quantum-confined Dirac semimetal is elucidated by establishing carrier control techniques in films.

Unconventional surface states protected by non-trivial bulk orders are sources of various exotic quantum transport in topological materials. One prominent example is the unique magnetic orbit, so-called Weyl semimetals where two spatially separated Fermi-arcs interconnected across bulk. The recent observation Hall Dirac semimetal Cd3As2 bulks have drawn attention to novel quantization phenomena possibly evolving from orbit. Here we report oscillation and its evolution into thin film samples,...

Searching for an ideal magnetic Weyl semimetal hosting only a single pair of points has been focal point systematic clarification its unique magnetotransport derived from the interplay between topology and magnetization. Among candidates, triangular-lattice antiferromagnet EuCd2As2 attracting special attention due to prediction phase in ferromagnetic state; however, transport properties low-carrier density samples have remained elusive. Here, we report molecular beam epitaxy growth films,...

Here we study nonmonotonic features which appear both in magnetoresistivity and anomalous Hall resistivity during the simple magnetization process, by systematically measuring type-II magnetic Weyl semimetal EuCd$_2$Sb$_2$ films over a wide carrier density range. We find that positive hump can be explained as manifestation of field-linear term generalized magnetoconductivity formula including Berry curvature. As also confirmed model calculation, negative pronounced near point energy case...

We report crystallographic, specific heat, transport, and magnetic properties of the recently discovered noncentrosymmetric 5$d$-electron superconductors CaIrSi${}_{3}$ (${T}_{\mathrm{c}}=3.6$ K) CaPtSi${}_{3}$ (${T}_{\mathrm{c}}=2.3$ K). The heat suggests that these are fully gapped. upper critical fields less than 1 T, consistent with limitation by conventional orbital depairing. High, non-Pauli-limited ${\ensuremath{\mu}}_{0}{H}_{\mathrm{c}2}$ values, often taken as a key signature novel...

The compound ${\text{InCu}}_{2/3}{\text{V}}_{1/3}{\text{O}}_{3}$ has been studied by spectroscopy in the IR, near-infrared, and visible regions. X-ray neutron diffraction indicate two-dimensional (2D) structural order of magnetic ${\text{Cu}}^{2+}$ $(S=1/2)$ ions on a honeycomb lattice with nonmagnetic ${\text{V}}^{5+}$ complementing hexagonal layer. Superstructure reflections observed reveal presence this 2D Cu/V domains approximately $300\text{ }\text{\AA{}}$ disordered stacking along $c$...

Advances in low-dimensional superconductivity are often realized through improvements material quality. Apart from a small group of organic materials, there is near absence clean-limit two-dimensional (2D) superconductors, which presents an impediment to the pursuit numerous long-standing predictions for exotic with fragile pairing symmetries. Here, we report development bulk superlattice consisting transition metal dichalcogenide (TMD) superconductor 2$H$-niobium disulfide (2$H$-NbS$_2$)...

Spin-orbit coupling (SOC) is pivotal for various fundamental spin-dependent phenomena in solids and their technological applications. In semiconductors, these have been so far studied relatively weak electron-electron interaction regimes, where the single electron picture holds. However, SOC can profoundly compete against Coulomb interaction, which could lead to emergence of unconventional electronic phases. Since depends on electric field crystal including contributions itinerant electrons,...