Spin Dynamics and Light-Induced Effects in EuZn${}_2$P${}_2$

Abstract

The magnetic spin dynamics and optical properties of EuZn${}_2$P${}_2$ are studied. Single crystals grown by the Sn-flux method crystallize in the $P\overline{3}m1$ (No.~164) space group and order antiferromagnetically at $T_N=23.5$~K. ${}^{151}$Eu Mössbauer spectroscopy confirms the presence of the Eu${}^{2+}$ oxidation state only and the magnetic moment angle relative to the $c$-axis is $\hat{I}¸=46(3)$\textdegree. Temperature-dependent electron spin resonance (ESR) measurements reveal that spin-spin interactions predominantly govern the spin relaxation mechanisms, as evidenced by the linewidth behavior ($\hat{I}”H$). Positive $g$-shifts ($\hat{I}”g)$ for $H\parallel ab$ indicate the presence of local electron polarization. The ESR data support the formation of anisotropic magnetic polarons, which trap spin carriers and contribute to increased electrical resistance. Angular-dependent ESR spectra at room temperature display anisotropic behavior in both $\hat{I}”g(\ddot{I}•)$ and $\hat{I}”H(\ddot{I}•)$, with a dominant three-dimensional component $C_{3D}$, indicative of robust interlayer coupling and antiferromagnetic fluctuations. Under light illumination, a small broadening of $\hat{I}”H$ is observed. Furthermore, a photovoltaic effect is identified in EuZn${}_2$P${}_2$, with photodetector performance metrics suggesting promising capabilities for future optoelectronic devices.

11 pages, 8 figures