Showing 138 results for Author: David S. Parker
Sep, 2026
Journal
The ideal Weyl "hydrogen-atom" semimetal exhibits only a single pair of Weyl nodes and no other trivial states at the Fermi energy. Such a material would be a panacea in the study of Weyl quasi-particles, allowing direct unambiguous observation of their topological properties. The alluaudite-like K2Mn3(AsO4)3 compound was recently proposed as such a material. Here, we us…
Aug, 2026
Journal
Th2Zn17−type structure-based permanent magnets, such as Sm2Fe17N3, offer strong potential as alternatives to neodymium magnets (NdFeB), but their practical use is limited by phase stability and the scarcity of Sm. Ce-based counterparts, particularly Ce2Fe17N3, are attractive low-cost candidates, yet their intrinsic planar magnetic anisotropy restricts permanent-magnet…
Aug, 2026
Journal
Here, we present our synthesis and characterization of the LnTi3(Sb,Sn)4 (Ln: Ce, Pr, Nd, Sm, Gd) family of cleavable kagome metals. While these materials are isostructural to the LnTi3Bi4 family, they only form as (Sb,Sn) solid-solutions with no corresponding LnTi3Sb4 or LnTi3Sn4 phases. We use a combination of first-principles density functional theory (DFT) and crystal…
Jun, 2026
Journal
The crystal structure and properties of CrAu3Sb6 are presented, determined by measurements on single crystal and polycrystalline samples and first-principles calculations. The trigonal structure (space group P3̅1m) comprises a CdI2-like sublattice of AuSb2 with Cr occupying octahedral holes in a fully ordered triangular array. It can be viewed as a variation of the interes…
Sep, 2025
Journal
We provide experimental evidence for the absence of a magnetic moment in bulk RuO2, a candidate altermagnetic material, by using a combination of Mössbauer spectroscopy, nuclear forward scattering, inelastic X-ray and neutron scattering, and density functional theory calculations. Using complementary Mössbauer and nuclear forward scattering, we determine the Ru magnetic hy…
Aug, 2025
Journal
We perform first-principles calculations on the Mo/Zr-alloyed ThMn12-structure prototype CeFe12 to explore its electronic and magnetic properties and potential for permanent magnet applications. A recent experiment has shown that the Mo/Zr-alloyed CeFe12 phase with the symmetry 𝐼4/𝑚𝑚𝑚 can be stabilized in bulk. It encourages an investigation into the intrinsic magnetic…
Aug, 2025
Journal
Y2Co3 is a newly discovered antiferromagnetic (AFM) compound with distorted kagome layers. Previous investigations via bulk magnetization measurements suggested a complex noncollinear magnetic behavior, with magnetic moments primarily anti-aligned along the 𝑏 axis and some canting towards the 𝑎𝑐 plane. In this study, we report the magnetic structure of Y2Co3 to be an A-…
Jun, 2025
Journal
HfCuSi2-type pnictogen compounds have recently been shown to be a versatile platform for designing materials with topologically nontrivial band structures. However, these phases require strict control over the electron count to tune the Fermi level, which can only be achieved in compositions with A2+M2+Pn2 and A3+M+Pn2 (A = lanthanides, M = transition metals, Pn = pnictoge…
May, 2025
Journal
Kagome metals with van Hove singularities near the Fermi level can host intriguing quantum phenomena such as chiral loop currents, electronic nematicity, and unconventional superconductivity. However, to our best knowledge, unconventional magnetic states driven by van Hove singularities–like spin-density waves–have not been observed experimentally in kagome metals. Here, w…
May, 2025
Journal
OsO4 and RuO4 are molecular oxides with unique tetrameric structures and rare +8 oxidation states. Accurately modeling their properties remains challenging for density functional theory (DFT) due to weak intertetramer interactions, which standard functionals fail to capture. Here, we show that the van der Waals (vdW)-corrected density functional (vdW-DF-optB86b) provides s…
May, 2025
Journal
All-inorganic lead-free halide double perovskites offer a promising avenue toward non-toxic, stable optoelectronic materials, properties that are missing in their prominent lead-containing counterparts. Their large thermopowers and high carrier mobilities also make them promising for thermoelectric applications. Here, we present a first-principles study of the lattice vibr…
Apr, 2025
Journal
We investigate and compare the electronic structure of OsO2 with the extensively studied RuO2. Calculations show that OsO2 exhibits antiferromagnetism and spin splitting driven by crystal symmetry, a characteristic of altermagnetism and similar to RuO2. Examination of the Fermi surface, with and without spin-orbit coupling, reveals that OsO2 has lower Fermi group velocitie…