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Novel compounds with two-dimensional square lattices formed by group IV or V elements (Si, Sn, Ge, Bi, and Sb) have been attracting a great deal of attention in recent times, mainly because of the possible emergence of various topological phases therein. Here, we successfully grow the single crystals of Sn-square-net based material $\mathrm{Sc}{\mathrm{Sn}}_{2}$, and systematically perform their magnetization and magnetotransport measurements. Clear quantum oscillations emerge in the magnetization isotherms along different field orientations, from which nonzero Berry phases are extracted, implying that $\mathrm{Sc}{\mathrm{Sn}}_{2}$ harbors three-dimensional Fermi surfaces and nontrivial electronic states. Similar to many other topological semimetals with extremely large magnetoresistance, $\mathrm{Sc}{\mathrm{Sn}}_{2}$ shows field-induced resistivity enhancement as well, which has been proven to be not of a gap opening origin. Besides, at low temperature, large magnetoresistance with a quasilinear field dependence is observed. Our analysis of the magnetotransport data finds that the quasilinear magnetoresistance in $\mathrm{Sc}{\mathrm{Sn}}_{2}$ cannot be understood by several familiar mechanisms proposed in the literature. These findings are expected to have far reaching implications for both the fundamental understanding and magnetoresistance device application of topological semimetal materials.

Optical emission of plasma induced by a pulsed laser ablating the surface of a randomly packed granular (RPG) material in air is investigated experimentally, taking sieved copper microspheres with discrete diameters, d, ranging from 49 to 390 \textmu{}m as examples. We find a steplike phenomenon (also called a critical-like phenomenon) in the dependence of plasma emission on the grain size: when d is less than a critical size, only weak emissions are detected; however, when d exceeds the critical size, the emissions abruptly become at least 5 times stronger. Such a phenomenon can be explained by considering the RPG material as a non-Newtonian fluid with a yield stress and an effective viscosity. Specifically, in the range of the grain size above (below) the critical value, the RPG target has a yield stress larger (smaller) than the shock pressure imparted by the energetic processes of plasma generation and expansion, and thus, behaves like an elastic solid (a viscous fluid) to assist (impede) the formation of the plasma with high temperature and high density as an optical emission source for spectrochemical analysis. This work not only has significance in assessing a lower size limit for direct multielement analysis of RPG material using laser-induced breakdown spectroscopy (LIBS), but also shows that the mechanical characteristics of RPG material may be probed using LIBS.

Synergic effect of electronic correlation and spin-orbit coupling is an emerging topic in topological materials. Central to this rapidly developing area are the prototypes of strongly correlated heavy-fermion systems. Recently, some Ce-based compounds are proposed to host intriguing topological nature, among which the electronic properties of CeSb are still under debate. In this paper, we report a comprehensive study combining magnetic and electronic transport measurements, and electronic band structure calculations of this compound to identify its topological nature. Quantum oscillations are clearly observed in both magnetization and magnetoresistance at high fields, from which one pocket with a nontrivial Berry phase is recognized. Angular-dependent magnetoresistance shows that this pocket is elongated in nature and corresponds to the electron pocket as observed in LaBi. Nontrivial electronic structure of CeSb is further confirmed by first-principle calculations, which arises from spin splitting in the fully polarized ferromagnetic state. These features indicate that magnetic-field can induce nontrivial topological electronic states in this prototypical Kondo semimetal.

The advent of nodal-line semimetals, i.e., systems in which the conduction and valence bands cross each other along a closed trajectory (line or loop) inside the Brillouin zone, has opened up a new arena for the exploration of topological condensed matter in which, due to a vanishing density of states near the Fermi level, electron correlation effects also may play an important role. Despite this conceptual richness, however, material realization of nodal-line (loop) fermions is rare with ${\mathrm{PbTaSe}}_{2}$, ZrSiS, and ${\mathrm{PtSn}}_{4}$ as the only promising known candidates. Here we report the synthesis and physical properties of a semimetal ${\mathrm{PdSn}}_{4}$ that is isostructural with ${\mathrm{PtSn}}_{4}$ yet possesses quasiparticles with significantly enhanced effective masses. In addition, ${\mathrm{PdSn}}_{4}$ displays an unusual polar angular magnetoresistance which, at a certain field orientation, varies linearly with fields up to 55 T. Our paper suggests that, in association with its homologue ${\mathrm{PtSn}}_{4}$ whose low-lying excitations recently were claimed to possess Dirac nodal arcs, ${\mathrm{PdSn}}_{4}$ may be a promising candidate in the search for novel topological states with enhanced correlation effects.

Non-Fermi-liquid (NFL) phenomena associated with correlation effects have been widely observed in the phase diagrams of unconventional superconducting families. Exploration of the correlation between the normal state NFL, regardless of its microscopic origins, and the superconductivity has been argued as a key to unveiling the mystery of the high-${T}_{c}$ pairing mechanism. Here we systematically investigate the pressure-dependent in-plane resistivity $(\ensuremath{\rho})$ and Hall coefficient $({R}_{H})$ of a high-quality 112-type Fe-based superconductor ${\mathrm{Ca}}_{1\ensuremath{-}x}{\mathrm{La}}_{x}{\mathrm{Fe}}_{1\ensuremath{-}y}{\mathrm{Co}}_{y}{\mathrm{As}}_{2}$ $(x=0.2,y=0.02)$. With increasing pressure, the normal-state resistivity of the studied sample exhibits a pronounced crossover from non-Fermi-liquid to Fermi-liquid behaviors. Accompanied with this crossover, ${T}_{c}$ is gradually suppressed. In parallel, the extremum in the Hall coefficient ${R}_{H}(T)$ curve, possibly due to anisotropic scattering induced by spin fluctuations, is also gradually suppressed. The symbiosis of NFL and superconductivity implies that these two phenomena are intimately related. Further study on the pressure-dependent upper critical field reveals that the two-band effects are also gradually weakened with increasing pressure and reduced to the one-band Werthamer-Helfand-Hohenberg limit in the low-${T}_{c}$ regime. Overall, our paper supports the picture that NFL, multigap, and extreme ${R}_{H}(T)$ are all of the same magnetic origin, i.e., the spin fluctuations in the 112 iron arsenide superconductors.