Eu₁₁Zn₄Sn₂As₁₂: A Ferromagnetic Zintl Semiconductor with a Layered Structure Featuring Extended Zn₄As₆ Sheets and Ethane-like Sn₂As₆ Units

Abstract

We report the synthesis, structure, and magnetic properties of a new Zintl phase and structure type, Eu11Zn4Sn2As12. The structure and composition of this phase have been established by single-crystal X-ray diffraction and electron microprobe analysis. Eu11Zn4Sn2As12 crystallizes in monoclinic space group C2/c (No. 15) with the following lattice parameters: a = 7.5679(4) Å, b = 13.0883(6) Å, c = 31.305(2) Å, and β = 94.8444(7)° [R 1 = 0.0398; wR 2 = 0.0633 (all data)]. The anisotropic structural features staggered ethane-like [Sn2As6]12– units and infinite ∞ 2[Zn2As3]5– sheets extended in the a–b plane. Eu cations fill the space between these anionic motifs. Temperature-dependent magnetic properties and magnetoresistance of this Zintl phase have been studied, and the electronic structure and chemical bonding were elucidated using first-principles quantum chemical calculations (TB-LMTO-ASA). Quantum chemical calculations show that the ethane-like units can be considered as consisting of covalent single bonds; however, the ∞ 2[Zn2As3]5– sheets are best described with delocalized bonding and there is evidence of Eu–As interactions. Temperature-dependent magnetization and transport properties between 2 and 300 K show a ferromagnetic transition at 15 K, a band gap of 0.04 eV, and negative colossal magnetoresistance.

Colossal magnetoresistance in a nonsymmorphic antiferromagnetic insulator

“…Here we experimentally investigate Zintl Eu 5 In 2 Sb 6 in single crystalline form. Low-carrier density magnetic materials containing Europium are prone to exhibiting colossal magnetoresistance (CMR) [14][15][16][17][18] . The strong exchange coupling between the spin of the carriers and the spins of the Eu 2+ background causes free carriers at low densities to self-trap in ferromagnetic clusters around the Eu sites, which gives rise to a quasiparticle called magnetic polaron 19 .…”

Exploratory Work in the Quaternary System of Ca–Eu–Cd–Sb: Synthesis, Crystal, and Electronic Structures of New Zintl Solid Solutions

“…Chemical modifications, such as doping, proved to be a convenient tool to optimize electronic properties of Zintl phases. In addition, introduction of extra components can sometimes yield unexpected multinary compounds with new structural features [12,13,14]. In this contribution, we report on the synthesis and the structural characterization of several quaternary phases that were discovered through exploratory work in the system, Ca–Eu–Cd–Sb.…”

Synthesis-enabled exploration of chiral and polar multivalent quaternary sulfides

“…Lowering of the reaction temperature to stabilize complex metastable or stable compounds is a common goal for solid state synthesis, [2][3][4][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] such as formation of metastable forms of RE oxychlorides via low-temperature pyrohydrolysis of (NH4)3REC16. 49 The mixing of the rare-earth and transition metals in the silicide precursors is somewhat akin to eutectic fluxes used in the Latturner group to make metal-rich intermetallics, [29][30][31][32][33][34] as well as flux syntheses of complex intermetallics performed by other groups. [2][3][4][35][36][37][38][39][40][41][42][43][44][45][46][47][48] In-situ powder X-ray diffract...…”