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arXiv · 2512.17123

Engineering a Correlated Narrow-Gap Semiconductor: Effects of Ga Substitution in EuZn$_2$P$_2$

M. Dutra·E. Marulanda·G. G. Vasques·J. F. Oliveira·P. C. Sabino·R. B. Delgado·L. Mendonça-Fereira·A. R. V. Benvenho·E. Baggio-Saitovitch·R. K. Machado·N. M. Kawahala·J. Munevar·M. A. Avila·F. G. G. Hernandez
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Abstract

The effect of Ga substitution on the electronic, magnetic, and low-energy responses of the Zintl phase EuZn$_2$P$_2$ is investigated by electrical transport, electron spin resonance (ESR), and terahertz time-domain spectroscopy (THz-TDS). Incorporating Ga into EuZn$_2$P$_2$ (EuZn$_{1.8}$Ga$_{0.2}$P$_2$) reduces the electrical resistivity, indicating enhanced free-carrier density and a narrowed semiconducting gap. ESR confirms the persistence of Eu$^{2+}$ moments while showing a crossover from a Lorentzian to a Dysonian lineshape, consistent with reduced skin depth, increased carrier density, and the emergence of diffusive contributions. Ga-substituted compound display pronounced negative magnetoresistance linked to magnetic-polaron formation. THz-TDS reveals strong low-frequency absorption and a notable enhancement of the Drude conductivity in the substituted material, together with an increased carrier scattering time and enhanced carrier-density--to--effective-mass ratio. These results demonstrate that Ga substitution tunes charge transport, carrier dynamics, and short-range magnetic correlations in EuZn$_2$P$_2$, establishing EuZn$_{1.8}$Ga$_{0.2}$P$_2$ as a promising platform for engineering correlated narrow-gap magnetic semiconductors with enhanced electronic and spin-dependent functionalities.

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M. Dutra, E. Marulanda, G. G. Vasques, J. F. Oliveira, P. C. Sabino, R. B. Delgado, L. Mendonça-Fereira, A. R. V. Benvenho, E. Baggio-Saitovitch, R. K. Machado, N. M. Kawahala, J. Munevar, M. A. Avila, F. G. G. Hernandez. 2025-12-18. Engineering a Correlated Narrow-Gap Semiconductor: Effects of Ga Substitution in EuZn$_2$P$_2$. https://doi.org/10.1002/aelm.70474

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