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Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations
CeNi2Sn2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Ce is bonded in a 12-coordinate geometry to eight Ni and eight Sn atoms. There are four shorter (3.27 Å) and four longer (3.42 Å) Ce–Ni bond lengths. There are four shorter (3.34 Å) and four longer (3.44 Å) Ce–Sn bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 8-coordinate geometry to four equivalent Ce and four equivalent Sn atoms. All Ni–Sn bond lengths are 2.56 Å. In the second Ni site, Ni is bonded in a 9-coordinate geometry to four equivalent Ce and five Sn atoms. There are one shorter (2.49 Å) and four longer (2.56 Å) Ni–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 12-coordinate geometry to four equivalent Ce and four equivalent Ni atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ce and five Ni atoms.
NiO6SnCl6 crystallizes in the trigonal R-3 space group. The structure is zero-dimensional and consists of three NiO6 clusters and three SnCl6 clusters. In each NiO6 cluster, Ni is bonded in an octahedral geometry to six equivalent O atoms. All Ni–O bond lengths are 1.95 Å. O is bonded in a single-bond geometry to one Ni atom. In each SnCl6 cluster, Sn is bonded in an octahedral geometry to six equivalent Cl atoms. All Sn–Cl bond lengths are 2.47 Å. Cl is bonded in a single-bond geometry to one Sn atom.
As a measure of the temperature response of the energy of matter, the heat capacity $C_p$ is a fundamental thermodynamic property. Its dependence on magnetic field, especially at low temperatures, yields insight into the electronic, phononic, and magnetic states of condensed matter. Here, we present a set of paramagnetic and ferromagnetic (Ti, Zr, Hf)NiFe x Sn half-Heusler composites that exhibit low-field (<3 T) maxima in $C_p$ and higher-field magnetic quenching of the heat capacity at temperatures below 10 K. Using rigorous statistical analysis, we attribute the effect to the existence of paramagnons within the compounds. To explain the lowest-temperature (<4 K), low-field declines in $C_p$, we derive a magnon model up to fourth order in dispersion. While the combined paramagnon and magnon model matches the data well, the fit parameters are significantly underdetermined. Further, we provide a qualitative explanation of the secondary effect based on superconducting phases within the composites. Overall, our work highlights the insight of field-dependent heat capacity studies at fixed temperatures that cannot be as easily gleaned from the temperature-dependent heat capacity at fixed magnetic fields.