Evidence of unconventional superconductivity on the surface of the nodal semimetal CaAgPdP.

Surface states of topological materials provide extreme electronic states for unconventional superconducting states. CaAgPdP is an ideal candidate for a nodal-line Dirac semimetal with drumhead surface states and no additional bulk bands. Here, we report that CaAgPdP has surface states that exhibit unconventional superconductivity (SC) around 1.

Superconductivity in High-Entropy Antimonide MPtSb (M = Equimolar Ru, Rh, Pd, and Ir).

The high-entropy concept was applied to the synthesis of transition-metal antimonides, MPtSb (M = equimolar Ru, Rh, Pd, and Ir). High-entropy antimonide samples crystallized in a pseudo-hexagonal NiAs-type crystal structure with a 6/ space group were successfully synthesized through a conventional solid-state reaction and subsequent quenching. A detailed investigation of the composition and equilibration conditions confirmed the reversible phase transition between a multiphase state at low temperature and an entropy-driven single-phase solid solution at high temperatures.

Regular-triangle trimer and charge order preserving the Anderson condition in the pyrochlore structure of CsWO.

Since the discovery of the Verwey transition in magnetite, transition metal compounds with pyrochlore structures have been intensively studied as a platform for realizing remarkable electronic phase transitions. We report on a phase transition that preserves the cubic symmetry of the β-pyrochlore oxide CsWO, where each of W 5d electrons are confined in regular-triangle W trimers. This trimer formation represents the self-organization of 5d electrons, which can be resolved into a charge order satisfying the Anderson condition in a nontrivial way, orbital order caused by the distortion of WO octahedra, and the formation of a spin-singlet pair in a regular-triangle trimer.

Giant isotropic negative thermal expansion in Y-doped samarium monosulfides by intra-atomic charge transfer.

Stimulated by strong demand for thermal expansion control from advanced modern industries, various giant negative thermal expansion (NTE) materials have been developed during the last decade. Nevertheless, most such materials exhibit anisotropic thermal expansion in the crystal lattice. Therefore, strains and cracks induced during repeated thermal cycling degrade their performance as thermal-expansion compensators.

Progress of Research in Negative Thermal Expansion Materials: Paradigm Shift in the Control of Thermal Expansion.

To meet strong demands for the control of thermal expansion necessary because of the advanced development of industrial technology, widely various giant negative thermal expansion (NTE) materials have been developed during the last decade. Discovery of large isotropic NTE in ZrWO has greatly advanced research on NTE deriving from its characteristic crystal structure, which is now classified as NTE. Materials classified in this category have increased rapidly.

Colossal negative thermal expansion in reduced layered ruthenate.

Large negative thermal expansion (NTE) has been discovered during the last decade in materials of various kinds, particularly materials associated with a magnetic, ferroelectric or charge-transfer phase transition. Such NTE materials have attracted considerable attention for use as thermal-expansion compensators. Here, we report the discovery of giant NTE for reduced layered ruthenate.

Giant barocaloric effect enhanced by the frustration of the antiferromagnetic phase in Mn3GaN.

First-order phase transitions are accompanied by a latent heat. Consequently, manipulating them by means of an external field causes a caloric effect. Although transitions from antiferromagnetic to paramagnetic states are not controlled by a magnetic field, a large barocaloric effect is expected when strong cross-correlations between the volume and magnetic order occur.

Magnetovolume effects in manganese nitrides with antiperovskite structure.

Magnetostructural correlations in antiperovskite manganese nitrides were investigated systematically for stoichiometric and solid solution MnCu A N (A = Co, Ni, Zn, Ga, Ge, Rh, Pd, Ag, In, Sn or Sb). This class of nitrides is attracting great attention because of their giant negative thermal expansion, which is achieved by doping Ge or Sn into the A site as a relaxant of the sharp volume contraction on heating (spontaneous volume magnetostriction ) because of the magnetovolume effects. The physical background of large and mechanism of how the volume contraction becomes gradual with temperature are central concerns for the physics and applications of these nitrides.

Negative thermal expansion materials: technological key for control of thermal expansion.

Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials.