An overview on the structural diversity of europium based ternary intermetallics

4f-Orbital mixing increases the magnetic susceptibility of Cp'3Eu

Traditional models of lanthanide electronic structure suggest that bonding is predominantly ionic, and that covalent orbital mixing is not an important factor in determining magnetic properties. Here, 4f orbital mixing and its impact on the magnetic susceptibility of Cp'3Eu (Cp' = C5H4SiMe3) was analyzed experimentally using magnetometry and X-ray absorption spectroscopy (XAS) methods at the C K-, Eu M5,4-, and L3-edges. Pre-edge features in the experimental and TDDFT-calculated C K-edge XAS spectra provided unequivocal evidence of C 2p and Eu 4f orbital mixing in the π-antibonding orbital of a' symmetry. The charge-transfer configurations resulting from 4f orbital mixing were identified spectroscopically by using Eu M5,4-edge and L3-edge XAS. Modeling of variable-temperature magnetic susceptibility data showed excellent agreement with the XAS results and indicated that increased magnetic susceptibility of Cp'3Eu is due to removal of the degeneracy of the 7F1 excited state due to mixing between the ligand and Eu 4f orbitals.

On the Ytterbium Valence and the Physical Properties in Selected Intermetallic Phases

The present review summarizes important aspects of the crystal chemistry of ytterbium-based intermetallic compounds along with a selection of their outstanding physical properties. These originate in many cases from the ytterbium valence. Different valence states are possible here, divalent (4f14), intermediate-valent, or trivalent (4f13) ytterbium, resulting in simple diamagnetic, Pauli or Curie-Weiss paramagnetic, or valence fluctuating behavior. Especially, some of the Yb3+ intermetallics have gained deep interest due to their Kondo or heavy Fermion ground states. We have summarized their property investigations using magnetic and transport measurements, specific heat data, NMR, ESR, and Mössbauer spectroscopy, elastic and inelastic neutron scattering, and XAS data as well as detailed thermoelectric measurements.

Experiment and Theory in Concert To Unravel the Remarkable Electronic Properties of Na-Doped Eu11Zn4Sn2As12: A Layered Zintl Phase

Low-dimensional materials have unique optical, electronic, mechanical, and chemical properties that make them desirable for a wide range of applications. Nano-scaling materials to confine transport in at least one direction is a common method of designing materials with low-dimensional electronic structures. However, bulk materials give rise to low-dimensional electronic structures when bonding is highly anisotropic. Layered Zintl phases are excellent candidates for investigation due to their directional bonding, structural variety, and tunability. However, the complexity of the structure and composition of many layered Zintl phases poses a challenge for producing phase-pure bulk samples to characterize. Eu11Zn4Sn2As12 is a layered Zintl phase of significant complexity that is of interest for its magnetic, electronic, and thermoelectric properties. To prepare phase-pure Eu11-xNaxZn4Sn2As12, a binary EuAs phase was employed as a precursor, along with NaH. Experimental measurements reveal low thermal conductivity and a high Seebeck coefficient, while theoretical electronic structure calculations reveal a transition from a 3D to 2D electronic structure with increasing carrier concentration. Simulated thermoelectric properties also indicate anisotropic transport, and thermoelectric property measurements confirm the nonparabolicity of the relevant bands near the Fermi energy. Thermoelectric efficiency is known to improve as the dimensionality of the electronic structure is decreased, making this a promising material for further optimization and opening the door to further exploitation of layered Zintl phases with low-dimensional electronic structures for thermoelectric applications.

Cobalt-Induced Phase Transformation of Ni3Ga4 Generates Chiral Intermetallic Co3Ni3Ga8

The scientific community has found immense difficulty to focus on the generation of chiral intermetallics compared to the chiral molecular structure, probably due to the technical difficulty in producing them as no general controlled protocol is available. Herein, using a conventional metal flux technique, we have discovered a new ternary intermetallic Co₃Ni₃Ga₈, substituting Co at the Ni sublattice in a highly symmetric Ni₃Ga₄ (Ia3̅d). Co₃Ni₃Ga₈ crystallizes in the I4₁32 space group, a Sohncke type, and can host the chiral structure. To the best of our knowledge, this is the first report of a ternary intermetallic crystallizing in this space group. The chiral structure of Co₃Ni₃Ga₈ is comprehensively mapped by various techniques such as single-crystal X-ray diffraction (XRD), synchrotron powder XRD, X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM) and theoretically studied using density functional theory. The discovery of this chiral compound can inspire the researchers to design hidden ternary chiral intermetallics to study the exotic electrical and magnetic properties.

Canted antiferromagnetic order in EuZn2As2 single crystals

Compounds containing Eu show a vast range of unique physical properties due to the interplay of electronic and magnetic properties, which can lead to a nontrivial electronic topology combined with magnetic order. We report on the growth of trigonal (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$P\overline{3 }m1$$\end{document}P3¯m1 space group) EuZn₂As₂ single crystals and on the studies of their structural, electronic and magnetic properties. A range of experimental techniques was applied including X-ray diffraction, electron microscopy, magnetic susceptibility, magnetization, heat capacity and Mössbauer spectroscopy in the study. We found that Eu has solely a 2+ valence state and its magnetic moments below T_N = 19.2 K form a canted antiferromagnetic structure, tilted from the basal plane.

Review on crystal structures and magnetic properties ofRTX3materials

The structural and compositional diversity of theRTX₃family of materials offers various magnetic and thermodynamic properties such as complex magnetic structure, vibronic bound states, heavy-fermions, valence fluctuations, metamagnetism, spin glass behavior, quantum criticality, and unconventional superconductivity. Here we present an overview of the crystal structures, crystal growth and magnetic properties ofRTX₃compounds as well as a discussion of the relevant physics. The magnetic properties of several compounds of theRTX₃family still remain unexplored. The compounds with a complex magnetic structure could potentially host exotic topological phases. This review article may help explore exotic magnetic properties such as the vibron state and topological spin textures.

Diversity in Crystal Structure and Physical Properties of RETX3 (RE - Rare Earth, T - Transition Metal, X - Main Group Element) Intermetallics

Rare Earth (re) based intermetallics are a fascinating class of inorganic compounds due to the presence of highly localized f-electrons. Among the ternary intermetallics, RETX₃ (RE - Rare Earth, T - Transition metals, X - 13-15th elements of the main groups) is one of the most widely studied RE-based intermetallic families in terms of diverse crystal structures as well as physical properties. This perspective presents a brief account of different structural variations observed in this family of compounds. We have also discussed structure-property correlations in selected compounds in this series that show interesting physical properties such as spin-glass behavior, superconductivity, heavy fermion behavior, Kondo behavior, etc. The origin of different physical properties of these compounds is also discussed in brief by correlating their crystal structures.

High Carrier Mobility in a Layered Antiferromagnet Integrated with Silicon

Coupling various functional properties in one material is always a challenge, more so if the material should be nanostructured for practical applications. Magnetism and high carrier mobility are key components for spintronic applications but rather difficult to bundle together. Here, we establish EuAl₂Si₂ as a layered antiferromagnet supporting high carrier mobility. Its topotactic synthesis via a sacrificial two-dimensional template results in epitaxial nanoscale films on silicon. Their outstanding structural quality and atomically sharp interfaces are demonstrated by diffraction and microscopy techniques. EuAl₂Si₂ films exhibit extreme magnetoresistance and a carrier mobility of above 10,000 cm² V^-1 s^-1. The marriage of these properties and magnetism makes EuAl₂Si₂ a promising spintronic material. Importantly, the seamless integration of EuAl₂Si₂ with silicon technology is particularly appealing for applications.

Deconvoluting the Magnetic Structure of the Commensurately Modulated Quinary Zintl Phase Eu11-xSrxZn4Sn2As12

The structure, magnetic properties, and ¹⁵¹Eu and ¹¹⁹Sn Mössbauer spectra of the solid-solution Eu_11-xSr_xZn₄Sn₂As₁₂ are presented. A new commensurately modulated structure is described for Eu₁₁Zn₄Sn₂As₁₂ (R3m space group, average structure) that closely resembles the original structural description in the monoclinic C2/c space group with layers of Eu, puckered hexagonal Zn₂As₃ sheets, and Zn₂As₆ ethane-like isolated pillars. The solid-solution Eu_11-xSr_xZn₄Sn₂As₁₂ (0 < x < 10) is found to crystallize in the commensurately modulated R3 space group, related to the parent phase but lacking the mirror symmetry. Eu₁₁Zn₄Sn₂As₁₂ orders with a saturation plateau at 1 T for 7 of the 11 Eu²⁺ cations ferromagnetically coupled (5 K) and shows colossal magnetoresistance at 15 K. The magnetic properties of Eu₁₁Zn₄Sn₂As₁₂ are investigated at higher fields, and the ferromagnetic saturation of all 11 Eu²⁺ cations occurs at ∼8 T. The temperature-dependent magnetic properties of the solid solution were investigated, and a nontrivial structure-magnetization correlation is revealed. The temperature-dependent ¹⁵¹Eu and ¹¹⁹Sn Mössbauer spectra confirm that the europium atoms in the structure are all Eu²⁺ and that the tin is consistent with an oxidation state of less than four in the intermetallic region. The spectral areas of both Eu(II) and Sn increase at the magnetic transition, indicating a magnetoelastic effect upon magnetic ordering.