We synthesized the ferromagnetic EuAgP semiconductor and conducted a comprehensive study of its crystalline, magnetic, heat capacity, band gap, and magnetoresistance properties. Our investigation utilized a combination of X-ray diffraction, optical, and PPMS DynaCool measurements. EuAgP adopts a hexagonal structure with the P63/mmc space group. As the temperature decreases, it undergoes a magnetic phase transition from high-temperature paramagnetism to low-temperature ferromagnetism. We determined the ferromagnetic transition temperature to be TC = 16.45(1) K by fitting the measured magnetic susceptibility using a Curie-Weiss law. Heat capacity analysis of EuAgP considered contributions from electrons, phonons, and magnons, revealing η = 0.03 J/(mol·K2), indicative of semiconducting behavior. Additionally, we calculated a band gap of ∼1.324(4) eV based on absorption spectrum measurements. The resistivity versus temperature of EuAgP measured in the absence of an applied magnetic field shows a pronounced peak around TC, which diminishes rapidly with increasing applied magnetic fields, ranging from 1 T to 14 T. An intriguing phenomenon emerges in the form of a distinct magnetoresistance transition, shifting from positive (e.g., 1.95% at 300 K and 14 T) to negative (e.g., −30.73% at 14.25 K and 14 T) as the temperature decreases. This behavior could be attributed to spin-disordered scattering.

中文翻译：

---

EuAgP 半导体中具有符号反转的晶体、铁磁性和磁阻


我们合成了铁磁 EuAgP 半导体，并对其晶体、磁性、热容、带隙和磁阻特性进行了全面研究。我们的研究结合了 X 射线衍射、光学和 PPMS DynaCool 测量。EuAgP 采用 P63/mmc 空间群的六边形结构。随着温度的降低，它经历了从高温顺磁性到低温铁磁性的磁相转变。我们通过使用居里-魏斯定律拟合测得的磁化率，确定铁磁转变温度为 TC = 16.45（1） K。EuAgP 的热容分析考虑了电子、声子和磁振子的贡献，显示 η = 0.03 J/（mol·K2），指示半导体行为。此外，我们根据吸收光谱测量计算出 ∼1.324（4） eV 的带隙。在没有外加磁场的情况下测得的 EuAgP 的电阻率与温度的关系显示 TC 周围有一个明显的峰值，随着外加磁场的增加，该峰值迅速减弱，范围从 1 T 到 14 T。一个有趣的现象以明显的磁阻转变的形式出现，随着温度的降低，从正（例如，在 300 K 和 14 T 时为 1.95%）转变为负（例如，在 14.25 K 和 14 T 时为 -30.73%）。这种行为可归因于自旋无序散射。