We report measurements of the de Haas-van Alphen effect on a series of compounds, LaMIn5 (M=Co,Rh,Ir). The results show that each of the Co and Ir Fermi surfaces (FSs) exhibits some portions that are two dimensional and some portions that are three dimensional. The most two-dimensional character is exhibited in LaCoIn5, less two-dimensional behavior is seen in LaIrIn5, and no part of Fermi surface of LaRhIn5 is found to have a two-dimensional character. Thus the two dimensionality of portions of the FSs is largely determined by the d character of the energy bands while all of the effective masses remain ≤1.2. This fact has implications for the causes of the heavy fermion nature of superconductivity and magnetism in the Ce-based compounds having similar composition and structure. © 2009 The American Physical Society.

The magnetic, thermal, and transport properties of single crystals of the narrow gap semiconductor Ce3 Au3 Sb4 have been studied. Transport data are consistent with an exponential activation and variable range hopping at low temperatures, which is characteristic of weak disorder and localization. The specific heat and the magnetic susceptibility data suggest the existence of a large density of states of localized states in the gap. The physics is then different from standard Kondo insulators. From its unique physical properties, we propose a three band model (valence, conduction, and f bands) with weak disorder that explains most of the experimental findings. © 2007 The American Physical Society.

Magnetic topological semimetals allow for an effective control of the topological electronic states by tuning the spin configuration. Among them, Weyl nodal line semimetals are thought to have the greatest tunability, yet they are the least studied experimentally due to the scarcity of material candidates. Here, using a combination of angle-resolved photoemission spectroscopy and quantum oscillation measurements, together with density functional theory calculations, we identify the square-net compound EuGa4 as a magnetic Weyl nodal ring semimetal, in which the line nodes form closed rings near the Fermi level. The Weyl nodal ring states show distinct Landau quantization with clear spin splitting upon application of a magnetic field. At 2 K in a field of 14 T, the transverse magnetoresistance of EuGa4 exceeds 200,000%, which is more than two orders of magnitude larger than that of other known magnetic topological semimetals. Our theoretical model suggests that the non-saturating magnetoresistance up to 40 T arises as a consequence of the nodal ring state.

Magnetism in two-dimensional (2D) van der Waals (vdW) materials has recently emerged as one of the most promising areas in condensed matter research, with many exciting emerging properties and significant potential for applications ranging from topological magnonics to low-power spintronics, quantum computing, and optical communications. In the brief time after their discovery, 2D magnets have blossomed into a rich area for investigation, where fundamental concepts in magnetism are challenged by the behavior of spins that can develop at the single layer limit. However, much effort is still needed in multiple fronts before 2D magnets can be routinely used for practical implementations. In this comprehensive review, prominent authors with expertise in complementary fields of 2D magnetism (i.e., synthesis, device engineering, magneto-optics, imaging, transport, mechanics, spin excitations, and theory and simulations) have joined together to provide a genome of current knowledge and a guideline for future developments in 2D magnetic materials research.