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We present the microscopic origin of the ferromagnetism of Fe0.25TaS2 and its finite-temperature magnetic properties. The band structures of Fe0.25TaS2 are first obtained by the first-principles calculations and it is found that both conventional and Dirac carriers coexist in metallic Fe0.25TaS2. Accordingly, considering the spin-orbit coupling of Fe 3d ion, we derive an effective Ruderman–Kittle–Kasuya–Yosida-type Hamiltonian between Fe spins in the presence of both the conventional parabolic-dispersion and the Dirac linear-dispersion carriers, which contains a Heisenberg-like, an Ising-like and an XY-like term. In addition, we obtain the ferromagnetic Curie temperature Tc by using the cluster self-consistent field method. Our results could address not only the high ferromagnetic Curie temperature but also the large magnetic anisotropy in FexTaS2. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the Raman and photoluminescence spectra of Y2O3/Eu3+ and Y2O3/Eu3+/Mg2+ nanorods under high pressures using 514-nm and 532-nm laser light excitation. We observe transitions from the initial cubic phase to amorphous at pressures higher than 24 GPa for both Y2O3/Eu3+ and Y2O3/Eu3+/Mg2+ nanorods. In addition, Y2O3/Eu3+ and Y2O3/Eu3+/Mg2+ nanorods exhibit different distorted states after the pressure has been raised to 8 GPa. The analyses of intensity ratios, I0−2/I0−1 from 5D0–7F2 to 5D0–7F1 and I0−2A/B of 5D0–7F2 transitions indicate that Y2O3/Eu3+/Mg2+ nanorods exhibit stronger local micro-surrounding characteristics for Eu3+ ions in a pressure-modulated crystal field. The doped Mg2+ ion results in reducing the crystal ionicity in the distorted lattice state under high pressures. The use of doped ions as an ion modifier can be applied to the study of small local microstructural changes through Eu3+ luminescence. [ABSTRACT FROM AUTHOR]