本文报道了Zintl相化合物EuIn $_2$ P $_2$的磁光研究结果。该化合物在$T_C$ =24 K时磁性有序，并表现出伴随的大磁阻效应。对于$T\le$ 50 K和不断增加的磁场，我们观察到转移的光谱重量在$σ_1(ω)$从1电子伏特以上的能量到低能量的金属成分，以及到一个中红外信号集中在约600厘米$^{-1}$。后一种吸收让人想起在大量所谓的近藤材料中所看到的，并归因于跨越杂化间隙的激发。随着磁场的增加，观察到的德鲁德重量的增加表明，由于磁化强度的增加，流动电荷载流子浓度的增强，这是之前在表现出巨大磁阻效应的其他化合物中观察到的现象。
英文摘要：
We report results of a magneto-optical investigation of the Zintl-phase compound EuIn$_2$P$_2$. The compound orders magnetically at $T_C$=24 K and exhibits concomitant large magnetoresistance effects. For $T\le$50 K and increasing magnetic fields we observe a transfer of spectral weight in $σ_1(ω)$ from energies above 1 eV into the low-energy metallic component as well as into a mid-infrared signal centered at about 600 cm$^{-1}$. This latter absorption is reminiscent to what has been seen in a large variety of so-called Kondo materials and ascribed to excitations across the hybridization gap. The observed gain of Drude weight upon increasing magnetic field suggests an enhancement of the itinerant charge-carrier concentration due to the increasing magnetization, a phenomenon that was previously observed in other compounds which exhibit colossal magnetoresistive effects.
Field-induced Topological Hall effect in antiferromagnetic axion insulator candidate EuIn$_2$As$_2$
磁性拓扑材料因其潜在的实现各种新量子现象的能力而引起人们的极大关注。EuIn $_2$ As $_2$最近在理论上被认为是期待已久的本征反铁磁体轴子绝缘体。然而，在这种材料中的拓扑状态引起的输运性质的实验研究是稀缺的。在本文中，我们进行了详细的磁阻（MR）和霍尔测量来研究这种材料的磁输运性质。我们发现，运输强烈影响的自旋配置的Eu时刻从伴随的变化的场依赖性的MR和低于Néel温度的磁化强度。最重要的是，观察到异常霍尔效应（AHE）和大的拓扑霍尔效应（THE）。我们认为AHE起源于螺旋自旋结构引起的非零净Berry曲率，而THE归因于外磁场诱导EuIn $_2$ As $_2$形成的具有有限标量自旋手征的非共面自旋织构.我们的研究提供了一个平台，以了解电子能带的拓扑结构和场致磁结构之间的相互作用对磁电输运性质的影响。此外，我们的观测结果还为通过调控EuIn $_2$ As $_2$的磁态实现轴子绝缘体态和高阶拓扑绝缘体态提供了线索.
In-plane antiferromagnetic moments in axion topological insulator candidate EuIn$_2$As$_2$
具有反铁磁序的拓扑绝缘体可以作为实现轴子电动力学的理想平台。本文报道了轴子拓扑绝缘体候选体EuIn $_2$ As $_2$的系统研究。费米能级上的线性能量色散证实了所提出的空穴型费米口袋的存在。自旋翻转转变发生在$ab$ -平面内施加磁场，而不存在平行于$c$ -轴的场。观察到各向异性的磁相图和地面磁矩的取向被发现是在$ab$平面内。EuIn $_2$ As $_2$的磁电阻率表现为非单调的磁场强度的函数。由于磁场驱动和温度驱动的磁态，它表现出与角度相关的演化。这些结果表明，EuIn $_2$ As $_2$的磁态对输运性质和拓扑性质有很大的影响.
Magnetic field dependent variable range hopping behaviour in resistivity at low temperatures in polycrystalline colossal magnetoresistive manganites: evidence of spin polarised tunnelling
Critical Analysis of Skyrmionic Material Co$_{6.5}$Ru$_{1.5}$Zn$_8$Mn$_4$: a complex interplay of short and long-range interactions around the transition temperature
