title: Unusual Mn-Mn spin coupling in the polar intermetallic compounds CaMn2Sb2 and SrMn2Sb2.
abstract: Large single-crystals of two polar intermetallic phases, CaMn2Sb2 and SrMn2Sb2, have been grown using In or Sn as metal fluxes and characterized by single-crystal X-ray diffraction. The two compounds are isostructural and crystallize with the CaAl2Si2 structure (space group P3m1, No. 164) with unit cell parameters determined at 120(2) K of a = 4.5204(6) angstroms, c = 7.456(2) angstroms and a = 4.5802(17) angstroms, c = 7.730(5) angstroms for CaMn2Sb2 and SrMn2Sb2, respectively. Temperature- and field-dependent dc- and ac-magnetization measurements suggest complex magnetic ordering of the Mn moments below ca. 250 and 35 K for CaMn2Sb2 and below ca. 265 K for SrMn2Sb2. Resistivity measurements reveal metallic-like temperature dependence with rho(290) = 40 m omega cm for CaMn2Sb2 and rho290 = 100 m omega cm for SrMn2Sb2 with negligible magnetoresistance at 5 K in applied magnetic fields up to 10 kOe. Spin-polarized DFT electronic structure calculations confirm the metallic-like properties and provide further evidence for a magnetic structure where Mn atoms form two magnetic sublattices with ferromagnetic coupling within them and strong antiferromagnetic coupling between them.
authors: Department of Chemistry, University of Delaware, Newark, Delaware 19716, USA. sbobev@chem.udel.edu
authors: Svilen
authors: S
authors: Bobev
authors: Justin
authors: J
authors: Merz
authors: Ana
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authors: Lima
authors: Veronika
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authors: Fritsch
authors: Joe D
authors: JD
authors: Thompson
authors: John L
authors: JL
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authors: Gillessen
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