Excellence in Research:Single Crystal Growth and Investigation of Novel Exotic Fermion Materials

非技术摘要：我们今天使用的电子设备通过施加电压来控制负电荷电子在材料中的运动，即所谓的电流。然而，电子不仅具有电荷，还具有一种被称为本征自旋的性质，这类似于旋转的顶部。这导致了电子设备的发展，这种设备通过利用电子的电荷和自旋来发挥作用，这种新形式的电子被称为自旋电子学。虽然还处于初级阶段，但这一自旋电子学领域在超低功率电子和量子计算等应用领域具有深远的潜力。最近，一类新的材料被发现，称为费米子材料、拓扑绝缘体和半金属，或者仅仅是量子材料，这种材料允许电子电流同时使用电荷和自旋来控制。作为这一卓越研究项目的一部分，在国家科学基金会的支持下，诺福克州立大学(NSU)物理系和宾夕法尼亚州立大学2D晶体联盟-材料创新平台(2DCC-MIP)之间建立了新的战略伙伴关系。这两个小组之间的合作利用了他们各自在单晶生长、材料表征和建模方面的独特能力，组成了一个专注于发现新的Weyl半金属的团队，这是一种特定的固态晶体，是量子材料的良好候选者。此外，该项目还加强了晶体材料生长领域的教育和培训，国家研究委员会的报告《晶体物质的前沿》强调了这一领域的重要性。通过在NSU物理系和宾夕法尼亚州立大学2DCC-MIP为学生提供深入的研究培训，这项研究对至少9名物理专业本科生和一名材料科学研究生的教育、研究培训和专业发展产生了重大影响，这些学生在STEM领域都没有得到充分的代表。技术摘要：凝聚态物质中的拓扑费米子，如狄拉克和韦尔费米子，不仅具有根本的重要性，而且具有巨大的信息技术应用前景。虽然已经在各种材料中预测了3倍、6倍和8倍费米子，但这些预测仍有待实验验证。由于无法获得这些拟议候选材料的单晶样品，减缓了这一领域的进展。这一研究伙伴关系通过制定一项全面的战略来解决这一挑战，以生长和表征所提议的候选材料的单晶。这种方法加速了新型拓扑材料的发现。有兴趣的新的费米子候选材料包括：1)三重费米子Pd3Bi2S2，Ag3SeAu，A4Pn3(A=Ca，sr和Ba；Pn=As，Sb和Bi)，R4Pn3(R=La，Ce；Pn=As，Sb和Bi)和ReRh6Ge4(Re=Y，La和Lu)，2)6重费米子MgPt，PdAsS，K3BiTe3，Mg3Ru2，FeS2和PtP2，3)8重费米子CuBi2O4，PdBi2O4，PdS2O4，PdS，CSSN，CSSI，Ta3Sb，MP3DS4(M=稀土)和Nb3Bi.研究团队使用的材料表征包括磁传输、量子振荡和ARPES测量(在2DCCMIP上进行)和X射线衍射率、时间分辨反射率和在NSU进行的瞬变光栅测量。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Summary:The electronic devices we use today operate by controlling the motion of negatively charged electrons, known as an electric current, through a material by applying a voltage. However, electrons possess not only an electric charge but also a property known as their intrinsic spin, which is analogous to a spinning top. This has led to the development of electronic devices that function by exploiting both the charge and the spin of electrons in a new form of electricity known as spintronics. Although still in its infancy, this field of spintronics has far reaching potential in applications such as ultra-low power electronics and quantum computing. Recently, a new class of materials, known as fermion materials, topological insulators and semimetals, or just quantum materials, were discovered which allow electronic currents to be controlled using both charge and spin. As part of this Excellence in Research project, supported by the National Science Foundation, a new, strategic partnership between the Department of Physics at Norfolk State University (NSU) and the 2D Crystal Consortium-Materials Innovation Platform (2DCC-MIP) at Pennsylvania State University has been formed. The collaboration between the two groups leverages their respective unique capabilities in single crystal growth, materials characterization, and modeling into a team focused on the discovery of new Weyl semimetals, which are specific solid state crystals that are good candidates for quantum materials. Additionally, this project also strengthens education and training in the field of growth of crystalline materials, the importance of which was highlighted in the National Research Council's report "Frontiers in Crystalline Matter." By providing students with in-depth research training in the NSU Department of Physics and in 2DCC-MIP at Penn State this research has a significant impact on the education, research training, and professional development of at least nine undergraduate physics majors and a graduate student in material science, that are all underrepresented in STEM fields.Technical Summary:Topological fermions such as Dirac and Weyl fermions in condensed matter are not only of fundamental importance, but also carry great promise for information technology applications. Although 3-, 6- and 8-fold fermions have been predicted in a wide range of materials, these predictions are still awaiting experimental verification. The unavailability of single crystal samples of those proposed candidate materials has slowed the progress in this area. This research partnership addresses this challenge by developing a comprehensive strategy to grow and characterize single crystals of the proposed candidate materials. This approach accelerates discoveries of novel topological materials. The new fermion candidate materials which are of interest include: 1) 3-fold fermions Pd3Bi2S2, Ag3SeAu, A4Pn3 (A=Ca, Sr and Ba; Pn=As, Sb and Bi), R4Pn3 (R=La, Ce; Pn =As, Sb and Bi), and ReRh6Ge4 (Re = Y, La and Lu), 2) 6-fold fermions MgPt, PdAsS, K3BiTe3, Mg3Ru2, FeS2 and PtP2, and 3) 8-fold fermions CuBi2O4, PdBi2O4, PdS, CsSn, CsSi, Ta3Sb, MPd3S4(M=rare earth) and Nb3Bi. Materials characterization the research team uses include magnetotransport, quantum oscillation, and ARPES measurements (performed at 2DCCMIP) and XRD, time resolved reflectivity, and transient grating measurements performed at NSU.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.