A Novel Magnetic Material by Design: Observation of Yb3+ with Spin-1/2 in Yb x Pt5P

Single-Ion Behavior in New 2-D and 3-D Gadolinium 4f7 Materials: CsGd(SO4)2 and Cs[Gd(H2O)3(SO4)2]·H2O

The recent creation of 4f⁷ gadolinium materials has enabled vital studies of the free-ion properties of the Gd(III) cations. While the ⁸ S ground state in a trivalent Gd compound is, in principle, isotropic, it has been demonstrated that there is a residual orbital angular momentum affected by the crystal field and structural distortion in certain systems. By exploiting the atomistic control innate to material growth, we address a fundamental question of how the isotropic nature of Gd(III) is preserved in different dimensionalities of crystal structures. To achieve this, we designed two new trivalent Gd materials possessing two structurally distinct features, a 2-D CsGd(SO₄)₂ and a 3-D Cs[Gd(H₂O)₃(SO₄)₂]·H₂O. The tunability of the structural dimension is facilitated by O-H---O hydrogen bonds. The structural divergence between the two compounds allows us to investigate each material individually and make a comparison between them regarding their physical properties as a function of lattice dimension. Our results demonstrate that structural dimensions have a negligible effect on the single-ion behavior of the materials. Magnetization measurements for the Gd(III) complexes yielded paramagnetic states with the isotropic spin-only nature. Specific heat data suggest that there is a lack of magnetic phase transition down to T = 1.8 K, and coupled lattice vibrations in the materials are attributable to strong covalent bonding characters of the (SO₄)^2- and H₂O ligands. This work offers a pathway for retaining the single-ion property of Gd(III) while constructing the large spin magnetic moment S = 7/2 in large-scale extended frameworks.

Spin Reorientation in Antiferromagnetic MnPd5Se with an Anti-CeCoIn5 Structure Type

MnPd₅Se, a derivative of the anti-CeCoIn₅-type phase, was synthesized from a high-temperature solid-state reaction, structurally determined by X-ray diffraction, and magnetically characterized with a combined magnetic measurement and neutron powder diffraction (NPD). According to the X-ray diffraction results, MnPd₅Se crystallizes in a layered tetragonal structure with the same space group as CeCoIn₅, P4/mmm (No. 123). MnPd₅Se shows antiferromagnetic ordering around 80 K on the basis of the magnetic property measurements. An A-type antiferromagnetic structure was revealed from the analysis of neutron powder diffraction results at 300, 50, and 6 K. Moreover, a spin orientation rotation was observed as the temperature decreased. Pd L₃ X-ray absorption near edge spectroscopy results for MnPd₅Se semiqualitatively correlate with the calculated density of states supporting a nominal 0.2 electron transfer into the Pd d orbital from either Se or Mn in the compound. The discovery of MnPd₅Se, along with our previously reported MnT₅Pn (T = Pd or Pt; Pn = P or As), provides a tunable system for studying the magnetic ordering from ferromagnetism to antiferromagnetism with the strong spin-orbit coupling effect.

Chemistry in Superconductors

Superconductors with exotic physical properties are critical to current and future technology. In this review, we highlight several important superconducting families and focus on their crystal structure, chemical bonding, and superconductivity correlations. We connect superconducting materials with chemical bonding interactions based on their structure-property relationships, elucidating our empirically chemical approaches and other methods used in the discovery of new superconductors. Furthermore, we provide some technical strategies to synthesize superconductors and basic but important characterization for chemists needed when reporting new superconductors. In the end, we share our thoughts on how to make new superconductors and where chemists can work on in the superconductivity field. This review is written using chemical terms, with a focus on providing some chemically intuitive thoughts on superconducting materials design.