We investigate single crystals of the trigonal antiferromagnet ${\mathrm{EuZn}}_2{\mathrm{P}}_2$ ($P\overline{3}m1$) by means of electrical transport, magnetization measurements, x-ray magnetic scattering, optical reflectivity, angle-resolved photoemission spectroscopy (ARPES), and ab initio band structure calculations ($\mathrm{DFT}+U$). We find that the electrical resistivity of ${\mathrm{EuZn}}_2{\mathrm{P}}_2$ increases strongly upon cooling and can be suppressed in magnetic fields by several orders of magnitude (colossal magnetoresistance effect). Resonant magnetic scattering reveals a magnetic ordering vector of $q=\left(00\frac{1}{2}\right)$, corresponding to an $A$-type antiferromagnetic order, below $T_{\mathrm{N}}=23.7\mathrm{K}$. We find that the moments are canted out of the $a\text{−}a$ plane by an angle of about ${40}^{\circ }\pm {10}^{\circ }$ and aligned along the [100] direction in the $a\text{−}a$ plane. We observe nearly isotropic magnetization behavior for low fields and low temperatures which is consistent with the magnetic scattering results. The magnetization measurements show a deviation from the Curie-Weiss behavior below $\approx 150\mathrm{K}$, the temperature below which also the field dependence of the material's resistivity starts to increase. An analysis of the infrared reflectivity spectrum at $T=295\mathrm{K}$ allows us to resolve the main phonon bands and intraband and interband transitions, and estimate indirect and direct band gaps of $E_i^{\mathrm{opt}}=0.09$ and $E_d^{\mathrm{opt}}=0.33\mathrm{eV}$, respectively, which are in good agreement with the theoretically predicted ones. The experimental band structure obtained by ARPES is nearly $T$ independent above and below $T_{\mathrm{N}}$. The comparison of the theoretical and experimental data shows a weak intermixing of the Eu $4f$ states close to the $\mathrm{\Gamma }$ point with the bands formed by the phosphorous $3p$ orbitals leading to an induction of a small magnetic moment at the P sites.

• Received 1 March 2023
• Revised 5 June 2023
• Accepted 22 June 2023

DOI:https://doi.org/10.1103/PhysRevB.108.045116