Related Experiment Video
Updated: Aug 8, 2026

Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing
Published on: December 3, 2013
Unusual Mn-Mn spin coupling in the polar intermetallic compounds CaMn2Sb2 and SrMn2Sb2
Svilen Bobev1, Justin Merz, Ana Lima
1Department of Chemistry, University of Delaware, Newark, Delaware 19716, USA. sbobev@chem.udel.edu
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.
Related Concept Videos
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
Spin–Spin Coupling Constant: Overview
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Valence Bond Theory
Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the involved orbitals. The...
Spin–Spin Coupling: One-Bond Coupling
