Physical properties of intergrowth compound Eu2CuZn2P3

Abstract

The physical properties of single-crystalline Eu2⁢CuZn2⁢P3 were inspected via thermodynamic, transport, and neutron diffraction measurements. Eu2⁢CuZn2⁢P3 is composed of EuCuP and EuZn2⁢P2 motifs stacked in a one-to-one ratio. The magnetic response of Eu2⁢CuZn2⁢P3 is similar to that of EuZn2⁢P2 in its A-type antiferromagnetic (semiconducting) state. A Néel temperature of 𝑇𝑁=40.3K is obtained from the specific heat capacity. Single-crystal neutron diffraction reveals a (001) magnetic propagation vector, with primarily in-plane moments coupled along [001] in an up-up-down-down pattern. This spin structure retains the ferromagnetic EuCuP motifs and antiferromagnetic coupling across the EuZn2⁢P2 motifs. The electrical resistivity is characterized by metallic behavior above 100 K, an increase in 𝜌 upon cooling below ≈75K, and a large negative magnetoresistance below 𝑇N. First principles calculations evidence a narrow band gap for antiferromagnetic ordering and semimetallic behavior for the ferromagnetic state. This is consistent with the observed effect of magnetic field on the electrical resistivity. Hall effect measurements reveal a field-induced, negative anomalous Hall effect that increases on cooling down to 2 K. Also, an unconventional contribution to the Hall effect dominates the low-field Hall signal, particularly near 𝑇N, and is similar in appearance to a topological Hall effect. However, further work is necessary to understand if any of the transport properties have topological origins or if magnetism-induced modifications to the Fermi surface induce these unusual Hall effect signals in this and related materials.