Unveiling new topological phases of matter is one of the current objectives in condensed matter physics. Recent experimental discoveries of Dirac and Weyl semimetals prompt to search for other exotic phases of matter. Here we present a systematic angle-resolved photoemission spectroscopy (ARPES) study of ZrSiS, a prime topological nodal semimetal candidate. Our wider Brillouin zone (BZ) mapping shows multiple Fermi surface pockets such as the diamond-shaped Fermi surface, ellipsoidal-shaped Fermi surface, and a small electron pocket encircling at the zone center (Γ) point, the M point and the X point of the BZ, respectively. We experimentally establish the spinless nodal fermion semimetal phase in ZrSiS, which is supported by our first-principles calculations. Our findings evidence that the ZrSiS-type of material family is a new platform to explore exotic states of quantum matter, while these materials are expected to provide an avenue for engineering two-dimensional topological insulator systems.

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Single crystal of ternary uranium-based silicide U 2 NiSi 3 , which crystallizes with a disordered hexagonal AlB 2 -type structure, was investigated by means of magnetic, resistivity, heat capacity, and neutron-diffraction measurements. While dc magnetic characteristics and neutron-diffraction measurement give evidence for the long-range magnetic ordering, ac magnetic susceptibility, isothermal remanent magnetization, resistivity, and heat capacity data are consistent with spin-glass behavior. The obtained results suggest the formation in U 2 NiSi 3 of rather unusual state in which long-range magnetic ordering coexists with spin-glass freezing.

A single crystal of the uranium-based ternary silicide U 2 CoSi 3 has been investigated by means of magnetic, heat capacity, and electrical resistivity measurements, performed in wide ranges of the temperature and magnetic field. The compound crystallizes with a hexagonal AlB 2 -type structure with crystallographic disorder in the nonmagnetic atom sublattice. The results indicate the formation at low temperatures of a ferromagnetic clusterglass state, which likely originates from crystallographic disorder in the nonmagnetic atom sublattice of the hexagonal AlB 2 -type unit cell. The low-temperature behavior of the electrical resistivity of U 2 CoSi 3 can be adequately described in terms of theories developed for disordered systems.

Single crystal of Ce 2 RhSi 3 was investigated by means of x-ray diffraction, magnetization, electrical resistivity, and heat-capacity measurements. Moreover, its electronic structure was studied by cerium core-level x-ray photoemission spectroscopy. The results revealed that Ce 2 RhSi 3 is an antiferromagnetic Kondo lattice due to the presence of stable trivalent Ce ions.