Hybridization Gap and Dresselhaus Spin Splitting in EuIr4In2Ge4.

EuIr₄In₂Ge₄ is a new intermetallic semiconductor that adopts a non-centrosymmetric structure in the tetragonal ${I\bar 42m}$ space group with unit cell parameters a=6.9016(5) Å and c=8.7153(9) Å. The compound features an indirect optical band gap E_g=0.26(2) eV, and electronic-structure calculations show that the energy gap originates primarily from hybridization of the Ir 5d orbitals, with small contributions from the Ge 4p and In 5p orbitals. The strong spin-orbit coupling arising from the Ir atoms, and the lack of inversion symmetry leads to significant spin splitting, which is described by the Dresselhaus term, at both the conduction- and valence-band edges. The magnetic Eu²⁺ ions present in the structure, which do not play a role in gap formation, order antiferromagnetically at 2.5 K. [ABSTRACT FROM AUTHOR]