2-Dimensional (2D) CrPS4 single crystals have been grown by the chemical vapor transport method. The crystallographic, magnetic, electronic and thermal transport properties of the single crystals were investigated by the room-temperature X-ray diffraction, electrical resistivity \r{ho}(T), specific heat CP(T) and the electronic spin response (ESR) measurements. CrPS4 crystals crystallize into a monoclinic structure. The electrical resistivity \r{ho}(T) shows a semiconducting behavior with an energy gap Ea=0.166 eV. The antiferromagntic (AFM) transition temperature is about TN=36 K. The spin flipping induced by the applied magnetic field is observed along the c axis. The magnetic phase diagram of CrPS4 single crystal has been discussed. The extracted magnetic entropy at TN is about 10.8 J/mol K, which is consistent with the theoretical value R ln(2S + 1) for S = 3/2 of the Cr3+ ion. Based on the mean-field theory, the magnetic exchange constants J1 and Jc corresponding to the interactions of the intralayer and between layers are about 0.143 meV and -0.955 meV are obtained based on the fitting of the susceptibility above TN, which agree with the results obtained from the ESR measurements. With the help of the strain for tuning the magnetic properties, monolayer CrPS4 may be a promising candidate to explore 2D magnetic semiconductors.
Crystal growth and electronic properties of a 3D Rashba material, BiTeI, with adjusted carrier concentrations
3D Rashba材料可以成为自旋相关新现象的主要参与者,从金属极端(非常规超导性)到传输中间体(自旋霍尔效应)再到新的绝缘变体(3D拓扑绝缘态)。作为这种3D Rashba材料的基础和应用研究的重要支柱,这项研究建立了候选化合物BiTeI的相当大的单晶的生长,并调整了载流子浓度。采用三种技术(标准垂直布里奇曼、改进的水平布里奇曼和蒸气传输),并通过所选技术成功地生长了具有从金属到绝缘的根本不同的电子状态的BiTeI晶体(> 1 * 1 * 0.2 mm 3)。通过相对论第一性原理计算,得到了BiTeI晶体中载流子浓度的三维Rashba电子态,包括费米面拓扑.
Magnetization, crystal structure and anisotropic thermal expansion of single-crystal SrEr2O4
采用PPMS测量和高分辨率同步辐射X射线粉末衍射研究了近化学计量比的Sr $_{1.04(3)}$ Er $_{2.09(6)}$ O $_{4.00(1)}$单晶的磁化强度、晶体结构和热膨胀。没有证据表明,任何结构相变,甚至高达500 K。晶格常数和晶胞体积的平均热膨胀与仅考虑声子对绝缘体的贡献的一阶Grüneisen近似一致,显示出沿晶体学\emph{a}、\emph{b}和\emph{c}轴的各向异性特征。我们的磁化强度测量表明,在低于$\sim$ 15 K的温度下出现明显的磁挫挫,反铁磁关联可以持续到300 K。
Anisotropic superconductivity and unusually robust electronic critical field in single crystal La$_{7}$Ir$_{3}$
报道了多晶La $_{7}$ Ir $_{3}$显示超导性破坏时间反演对称性,同时也具有各向同性的$s$ -波隙。这种非中心对称超导体的单晶对于理解该系统中电子配对机制的性质是非常必要的。本文报道了用提拉法生长La $_{7}$ Ir $_{3}$高质量单晶。利用X射线、磁化强度、电阻率和热容测量研究了这些大晶体的结构和超导性质。我们观察到一个明确的各向异性,在较低和较高的临界磁场施加平行和垂直于六角$c$轴的磁场。我们还报告了一个强大的电子临界场的存在下,偏离从热容量,这是表面超导性的标志来自上临界场。
Crystal structure stability and electronic properties of layered nickelate La$_4$Ni$_3$O$_{10}$
采用量子力学方法,在密度泛函理论的框架下研究了三层结构的镍酸盐$_4$ $_3$ O $_{10}$的晶体结构和电子性质.我们发现,在低温下,$_4$ $_3$ O $_{10}$经历了一个迄今未见报道的结构相变,转变为一个新的单斜$P2_1/a$相.该相的电子性质与H. Li \emph{et al} .,Nat. Commun. \textbf{8},704(2017),并应在重点解释观察到的$\sim$ 140\,K金属-金属相变的模型中予以考虑。
Effects of Crystalline Electronic Field and Onsite Interorbital Interaction in Yb-based Quasicrystal and Approximant Crystal
为了深入了解最近在准晶体Yb $_{15}$ Al $_{34}$ Au $_{51}$和近似晶体(AC)Yb $_{14}$ Al $_{35}$ Au $_{51}$中发现的一种新的量子临界现象,我们讨论了在AC中Yb处的晶体电场(CEF)的性质,并表明由于Al/Au混合位的存在,在每个Yb位上会出现不均匀的CEF能级.然后通过在Yb的4f和5d轨道之间引入库仑排斥,构造了AC上电子态的极小模型。基态的数值计算表明,Yb价态的晶格常数依赖性很好地解释了最近通过在准晶和AC中Al和Au元素的系统替代所做的测量,其中准晶Yb $_{15}$ Al $_{34}$ Au $_{51}$正好位于Yb价态开始剧烈变化的点处。我们的计算令人信服地表明,这确实是证据,该材料是位于量子临界点的Yb-价跃迁。
Metallic ground state and glassy transport in single crystalline URh$_2$Ge$_2$: Enhancement of disorder effects in a strongly correlated electron system
本文详细研究了中等无序重费米子系统URh $_2$ Ge $_2$的电子输运性质。对于这种材料,我们发现在一个单一的晶体化合物的玻璃态电子输运。我们推导出的电导率的温度依赖性,并建立通过光学电导率和霍尔效应测量的金属性。电子输运性质的整体行为非常类似于金属玻璃,在低温下额外的轻微自旋无序的贡献。我们认为,这种玻璃态的电子行为在晶体化合物中反映了增强的无序效应的结果,强的电子相关。
Nanyang Technological University(南洋理工大学);Sun Yat-Sen University (Zhuhai Campus)(中山大学(珠海校区));Nanjing University of Aeronautics and Astronautics(南京航空航天大学);École Polytechnique Fédérale de Lausanne (EPFL)(洛桑联邦理工学院);National Institute for Materials Science(物质材料研究机构);University of Science and Technology of China(中国科学技术大学);Sun Yat-Sen University (Guangzhou Campus)(中山大学(广州校区))