Design, synthesis, and physical properties of the intergrowth compound Eu${}_2$CuZn${}_2$As${}_3$

Abstract

The rational combination of existing magnetic topological compounds presents a promising route for designing new topological materials. We report the synthesis and comprehensive characterization of the layered quaternary intergrowth compound Eu${}_2$CuZn${}_2$As${}_3$, which combines structural units of two known magnetic topological materials, EuCuAs and EuZn${}_2$As${}_2$. Eu${}_2$CuZn${}_2$As${}_3$ exhibits an antiferromagnetic ground state with successive magnetic transitions: quasi-two-dimensional ordering at $T_{\mathrm{M}}=29.3$\,K, long-range antiferromagnetic ordering at $T_{\mathrm{N}}=19$\,K, and spin-reorientation at $T_{\mathrm{SR}}=16.3$\,K. The stepwise magnetic transitions manifest as plateau-like anomalies in the heat capacity. These transitions originate from multiple superexchange pathways and periodic variation of interplane Eu-Eu distances in the intergrowth structure. Charge transport shows a pronounced resistivity increase above $T_{\mathrm{N}}$ followed by minimal change below the ordering temperature. Magnetic fields rapidly suppress this resistivity rise, yielding significant negative magnetoresistance. Remarkably, Eu${}_2$CuZn${}_2$As${}_3$ inherits the nonlinear anomalous Hall effect characteristic of its parent compounds. Energy evaluations of collinear spin configurations reveal a lowest-energy state with ferromagnetic coupling between Eu planes in EuCuAs units while maintaining antiferromagnetic coupling within EuZn${}_2$As${}_2$ units. The corresponding electronic structure displays potentially topologically nontrivial features. Our work demonstrates the efficacy of structural hybridization for discovering novel magnetic topological materials and establishes a general strategy for materials discovery.