Discovery of New Zintl Films and Nanowires Grown by Topotaxy Conversion of III-V Semiconductors

Man Suk Song; Lothar Houben; Jean Souza; Edanel Fishbein; Moshe Haim; Ambikesh Gupta; Yufei Zhao; Anna-Eden Kossoy; Binghai Yan; Haim Beidenkopf; Hadas Shtrikman

paper

Discovery of New Zintl Films and Nanowires Grown by Topotaxy Conversion of III-V Semiconductors

arXiv:2608.22989

Abstract

Zintl phases draw broad interest for their diverse structural, magnetic, thermoelectric, topological and optical properties. Recently, Zintl Eu $_{3}$ In $_{2}$ As $_{4}$ and Eu $_{5}$ In $_{2}$ As $_{6}$ nanowires with axion magneto-topology have been synthesized by molecular beam epitaxy via topotactic conversion of InAs wurtzite and zincblende nanowires. Here we extend this methodology, demonstrating that topotaxial mutual-exchange growth applies not only to a broader set of III-V semiconductors beyond InAs but also to three-dimensional substrates whose surfaces are converted into Zintl thin films, as well as to nanowires. We report the growth of two new compounds: Eu $_{5}$ Ga $_{2}$ As $_{6}$ thin films converted from GaAs substrates, and Eu $_{5}$ Al $_{2}$ As $_{6}$ thin films from AlAs films. We also convert GaAs nanowires of both wurtzite and zincblende structures into Eu $_{5}$ Ga $_{2}$ As $_{6}$ nanowires. Though the stoichiometry is the same as in the previously reported Eu $_{5}$ In $_{2}$ As $_{6}$ case, microscopy and diffraction reveal a single-phase Pnma symmetry group rather than Pbam, highlighting symmetry-guided topotactic pathways to new Zintl frameworks. The compounds host an intricate magnetic phase diagram with three magnetic transitions, including two distinct antiferromagnetic orders and a canted antiferromagnetic phase that evolves into another antiferromagnetic phase under applied field through a spin-flop transition. Ab initio calculations predict that both Zintls are semiconductors with gaps of 0.79 eV in Eu $_{5}$ Ga $_{2}$ As $_{6}$ and 0.90 eV in Eu $_{5}$ Al $_{2}$ As $_{6}$ . The lower symmetry and increased structural complexity suggest suppressed lattice thermal conductivity, pointing to thermoelectric potential alongside prospects in spintronics and detector technologies. These results give an epitaxy-compatible route for discovering and integrating magnetic Zintl thin films and nanowires directly from relevant III-V semiconductors.

47 pages, 20 figures, 2 tables