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Dirac semimetals feature Dirac cones with topologically nontrivial states in the bulk that are protected by crystalline symmetries. They attract considerable attention due to rich quantum states and properties of interest, such as high Fermi velocities, mobility, and small effective masses. Here, we show that a ternary intermetallic BaAuSb crystal hosts both trivial and nontrivial topological Dirac states in the bulk. The nontrivial Fermi-surface pocket at the Brillouin zone center is characterized with only a few hundredths of a bare electron mass and with very high mobility. All parts of the Fermi surface detected by quantum oscillations, topologically trivial or nontrivial, have carriers with unusually high Fermi velocities and small masses. These conducting states may be coupled with magnetic moments in materials where Ba is replaced by magnetic rare-earth atoms.

We report a detailed study of electrical and thermal transport properties in 2H-M_{x}TaS_{2} (M=Mn, Co) magnets where M atoms are intercalated in the van der Waals gap. The intercalation induces ferromagnetism (FM) with an easy-plane anisotropy in 2H-Mn_{x}TaS_{2}, but FM with a strong uniaxial anisotropy in 2H-Co_{0.22}TaS_{2}, which finally evolves into a three-dimensional antiferromagnetism (AFM) in 2H-Co_{0.34}TaS_{2}. Temperature-dependent electrical resistivity shows metallic behavior for all samples. Thermopower is negative in the whole temperature range for 2H-Co_{x}TaS_{2}, whereas the sign changes from negative to positive with increasing Mn for 2H-Mn_{x}TaS_{2}. The diffusive thermoelectric response dominates in both high- and low-temperature ranges for all samples. A clear kink in electrical resistivity, a weak anomaly in thermal conductivity, as well as a slope change in thermopower were observed at the magnetic transitions for 2H-Mn_{0.28}TaS_{2} (T_{c}≈ 82 K) and 2H-Co_{0.34}TaS_{2} (T_{N}≈ 36 K), respectively, albeit weaker for lower x crystals. Co-intercalation promoted FM to AFM transition is further confirmed by Hall resistivity; the sign change of the ordinary Hall coefficient indicates a multiband behavior in 2H-Co_{x}TaS_{2}.

We report ferromagnetism in 2H-Co_{0.22}TaS_{2} single crystals where Co atoms are intercalated in the van der Waals gap, and a systematic study of its magnetic critical behavior in the vicinity of T_{c}∼28 K. The obtained critical exponents β=0.43(2), γ=1.15(1), and δ=3.54(1) fulfill the Widom scaling relation δ=1+γ/β and follow the scaling equation. This indicates that the spin coupling in 2H-Co_{0.22}TaS_{2} is of three-dimensional Heisenberg type coupled with long-range magnetic interaction, and that the exchange interaction decays with distance as J(r)≈r^{−4.69}. 2H-Co_{0.22}TaS_{2} exhibits a weak temperature-dependent metallic behavior in resistivity and negative values of thermopower with dominant electron-type carriers, in which obvious anomalies were observed below T_{c} as well as the anomalous Hall effect (AHE). The linear scaling behavior between the modified anomalous Hall resistivity ρ_{xy}/μ_{0}H and longitudinal resistivity ρ_{xx}^{2}M/μ_{0}H implies that the origin of the AHE in 2H-Co_{0.22}TaS_{2} should be dominated by the extrinsic side-jump mechanism.

We report discovery of antiferromagnetic semimetal EuZnSb_{2}, obtained and studied in the form of single crystals. Electric resistivity, magnetic susceptibility, and heat capacity indicate antiferromagnetic order of Eu with T_{N} = 20 K. The effective moment of Eu^{2+} inferred from the magnetization and specific heat measurement is 3.5 μ_{B}, smaller than the theoretical value of Eu^{2+} due to presence of both Eu^{3+} and Eu^{2+}. Magnetic-field-dependent resistivity measurements suggest dominant quasi-two-dimensional Fermi surfaces whereas the first-principle calculations point to the presence of Dirac fermions. Therefore, EuZnSb_{2} could represent the first platform to study the interplay of dynamical charge fluctuations, localized magnetic 4f moments, and Dirac states with Sb orbital character.

Layered van der Waals ferromagnets are promising candidates for designing new spintronic devices. Here we investigated the critical properties and magnetocaloric effect connected with ferromagnetic transition in layered van der Waals VI_{3} single crystals. The critical exponents β=0.244(5) with a critical temperature T_{c}=50.10(2)K and γ=1.028(12) with T_{c}=49.97(5)K are obtained from the modified Arrott plot, whereas δ=5.24(2) is obtained from a critical isotherm analysis at T_{c}=50K. The magnetic entropy change −ΔS_{M}(T,H) features a maximum at T_{c}, i.e., −ΔS_{M}^{max}∼2.64(2.27)Jkg^{−1}K^{−1} with out-of-plane (in-plane) field change of 5 T. This is consistent with −ΔS_{M}^{max}∼2.80Jkg^{−1}K^{−1} deduced from heat capacity and the corresponding adiabatic temperature change ΔT_{ad}∼0.96K with out-of-plane field change of 5 T. The critical analysis suggests that the ferromagnetic phase transition in VI_{3} is situated close to a three- to two-dimensional critical point. The rescaled ΔS_{M}(T,H) curves collapse onto a universal curve, confirming a second-order type of the magnetic transition and reliability of the obtained critical exponents.