Abstract
The growth and study of materials showing novel topological states of matter is one of the frontiers in condensed matter physics. Among this class of materials, the nitride antiperovskite Cu3PdN has been proposed as a new three-dimensional Dirac semimetal. However, the experimental realization of Cu3PdN and the consequent study of its electronic properties have been hindered due to the difficulty of synthesizing this material. In this study, we report fabrication and both structural and transport characterization of epitaxial Cu3PdN thin films grown on (001)-oriented SrTiO3 substrates by reactive magnetron sputtering and post-annealed in NH3 atmosphere. The structural properties of the films, investigated by x-ray diffraction and scanning transmission electron microscopy, establish single phase Cu3PdN exhibiting cube-on-cube epitaxy (001)[100]Cu3PdN||(001)[100]SrTiO3. Electrical transport measurements of as-grown samples show metallic conduction with a small temperature coefficient of the resistivity of 1.5 × 10−4 K−1 and a positive Hall coefficient. Post-annealing in NH3 results in the reduction of the electrical resistivity accompanied by the Hall coefficient sign reversal. Using a combination of chemical composition analyses and ab initio band structure calculations, we discuss the interplay between nitrogen stoichiometry and magneto-transport results in the framework of the electronic band structure of Cu3PdN. Our successful growth of thin films of antiperovskite Cu3PdN opens the path to further investigate its physical properties and their dependence on dimensionality, strain engineering, and doping.
Highlights
The discovery of three-dimensional (3D) Dirac semimetal (DSM) phases in Na3Bi1,2 and Cd3As23–7 was a breakthrough in condensed matter physics as it launched the growth and study of 3D topological materials
Bulk 3D-DSMs, characterized by having Dirac-type energy dispersion in the 3D momentum k-space close to the Fermi level,[8] are usually viewed as bulk counterparts of graphene owing to their similar electronic structure and unique transport properties, including ultrahigh electron motility and giant magnetoresistance.[6,7]
Two groups independently proposed nitride antiperovskite Cu3PdN as a new 3DDSM material with three pairs of Dirac points stabilized by the C4 rotational crystal symmetry of Cu3PdN.[14,15]
Summary
The discovery of three-dimensional (3D) Dirac semimetal (DSM) phases in Na3Bi1,2 and Cd3As23–7 was a breakthrough in condensed matter physics as it launched the growth and study of 3D topological materials. Epitaxial thin films of Dirac semimetal antiperovskite Cu3PdN
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