Europium-M-phosphorus (M = manganese, tin, indium) intermetallics: Synthesis, crystallography, and physical properties

Chapter One is an introduction to the structural and physical property studies of several intermetallic phases.; Chapter Two presents the synthesis, structural characterization, magnetism, and magnetoresistance of two new compounds, Eu₁₄MnAs₁₁ and Eu₁₄MnP₁₁. Both compounds crystallize in the Ca ₁₄AlSb₁₁ structure type, which has a unique structural feature, Pn₃7−, that is best described as Pn 3− + Pn₂4−. They show ferromagnetic ordering at 74 K and 50 K, respectively. Both compounds exhibit large magnetoresistance (MR) at low temperatures (below 100 K). The MR is best classified as colossal MR because it is coincident with magnetic order. It is very large relative to other stoichiometric compound.; Chapter Three presents the Sn flux synthesis of single crystals of EuMn ₂P₂ and SrMn₂P₂. Both EuMn₂P ₂ and SrMn₂P₂ crystallized in the CaAl₂Si ₂ structure type. According to single crystal and bulk measurements, EuMn₂P₂ is an antiferromagnetic semiconductor with a Neél temperature of 18 K. Magnetic measurements of SrMn₂P ₂ single crystals are in agreement with previously published powder data, which showed a broad magnetic transition occurring across the entire temperature range measured.; Chapter Four presents the Sn flux synthesis of single crystals of the polar intermetallic EuSnP; the crystal structure is composed of a corrugated layer of Sn with P bonded to and Eu ions interspersed between the corrugated Sn layers. Magnetic data 1 show antiferromagrietic ordering (T_N = 21 K), and a Curie-Weiss analysis of the data is consistent with the assignment of Eu2+. A spin-reorientation occurs at ∼1.5 T (T = 2 K) indicating the presence of metamagnetism.; Chapter Five presents the Sn flux synthesis of single crystals of the novel compound, Eu₃InP₃. Corner-shared InP₄ tetrahedra form linear chains along [010], and Eu cations are distributed among the chains. Ferrimagnetic ordering at 20 K suggests the presence of a two magnetic sublattice system and a spin reorientation at ∼0.05 T (T = 2 K) indicates metamagnetism. A delocalized interpretation of the magnetism focusing on Eu-Eu pairs suggests that an indirect exchange mechanism may contribute to the magnetic behavior.