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

非技术总结：我们今天使用的电子设备通过施加电压来控制带负电荷的电子（称为电流）通过材料的运动来运行。然而，电子不仅具有电荷，还具有称为其固有自旋的性质，这类似于旋转的陀螺。这导致了电子器件的发展，这些电子器件通过利用电子的电荷和自旋来发挥作用，这种新的电形式被称为自旋电子学。尽管仍处于起步阶段，但自旋电子学这一领域在超低功耗电子和量子计算等应用中具有深远的潜力。最近，发现了一类新的材料，称为费米子材料，拓扑绝缘体和半金属，或者只是量子材料，它们允许使用电荷和自旋来控制电子电流。作为这项卓越研究项目的一部分，由国家科学基金会支持，诺福克州立大学（NSU）物理系与宾夕法尼亚州立大学的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。两个小组之间的合作利用各自在单晶生长、材料表征和建模方面的独特能力，组建了一个专注于发现新外尔半金属的团队，这些半金属是特定的固态晶体，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，国家研究理事会的报告“晶体物质前沿”强调了这一点的重要性。“通过在NSU物理系和宾夕法尼亚州立大学的2DCC-MIP为学生提供深入的研究培训，这项研究对至少9名本科物理专业学生和1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领域的代表性都很低。凝聚态中的狄拉克费米子和外尔费米子等拓扑费米子不仅具有重要的物理意义，而且在信息技术中有着重要的应用前景。虽然3-，6-和8-fold费米子已被预测在广泛的材料，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。该研究伙伴关系通过制定一项全面的战略来生长和表征拟议候选材料的单晶来应对这一挑战。这种方法加速了新型拓扑材料的发现。新的费米子候选材料包括：1）三重费米子Pd_3Bi_2S_2，Ag_3SeAu，A_4Pn_3（A=Ca、Sr和Ba; Pn=As、Sb和Bi），R4Pn3（R=La，Ce; Pn =As、Sb和Bi）和ReRh 6 Ge 4（Re = Y、La和Lu），2）6重费米子MgPt、PdAsS、K3 BiTe 3、Mg3 Ru 2、FeS 2和PtP 2，和3）8重费米子CuBi 2 O 4、PdBi 2 O 4、PdS、CsSn、CsSi、Ta 3 Sb，Mpd 3S 4（M=稀土）和Nb 3Bi。研究团队使用的材料表征包括磁输运，量子振荡和ARPES测量（在2DCCMIP进行）和XRD，时间分辨反射率和NSU进行的瞬态光栅测量。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.