Hybridization Gap and Dresselhaus Spin Splitting in EuIr4In2Ge4

• Published in: Angewandte Chemie (International ed.) Vol. 54; no. 32; pp. 9186 - 9191
• Main Authors: Calta, Nicholas P., Im, Jino, Rodriguez, Alexandra P., Fang, Lei, Bugaris, Daniel E., Chasapis, Thomas C., Freeman, Arthur J., Kanatzidis, Mercouri G.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 03.08.2015; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: crystal growth; electronic structure; hybridization; intermetallic phases; X-ray diffraction; X-ray diffraction; crystal growth; hybridization; intermetallic phases; electronic structure
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201504315

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 Eg=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. An intermetallic semiconductor with a non‐centrosymmetric structure and the chemical formula EuIr4In2Ge4 is reported. The band gap is a direct result of strong IrIr bonding, and strong spin–orbit coupling effects lead to spin splitting at the conduction‐ and valence‐band edges, which is described by the Dresselhaus term.