Acquisition of a High-Magnetic-Field/Low-Temperature Facility for Materials Research with Synchrotron X-Rays

9802737 greven同步加速器x射线散射在材料科学和凝聚态物理中发挥着越来越重要的作用。该合同为获得一个几乎独一无二的高磁场/低温设备提供了部分支持，该设备将在美国主要的同步加速器x射线源之一斯坦福同步加速器辐射实验室（SSRL）运行。这个新设备将允许研究新材料的结构和磁性，具有同步加速器产生的x射线所特有的高动量分辨率，磁场高达13特斯拉，温度超过三个数量级，0.3K T 400K。该科学计划涉及对电子-电子相互作用起重要作用的材料的研究。这种“相关电子”材料处于凝聚态物理的前沿，它们为发现、观察和表征基本现象提供了无数的可能性。例如，在钙钛矿衍生结构的电荷载流子掺杂的反铁磁绝缘体中，强电子-电子相关性已知会导致多种特性：(i)绝缘体-金属转变，（ii）高温超导性，（iii）巨磁阻，（iv）电荷有序相，(v)和自旋有序相。在这些体系中，结构、磁性和电子性质通常是紧密耦合的，磁场的存在经常导致新相的形成。该科学计划涉及电荷、共振磁和非共振磁x射线散射技术。它还将涉及就地传输测量，以同时获得结构、磁和电子信息。此外，它将受益于补充研究，包括单晶的生长和表征，中子散射实验，以及与斯坦福大学正在进行的光电发射光谱研究的合作。这个新的高磁场/低温同步加速器x射线设施将使研究人员能够在材料科学和凝聚态物理的前沿进行研究，它将有助于培养具有材料科学，应用科学和物理学背景的新一代本科生和研究生。%%%***

9802737GrevenSynchrotron X-ray scattering plays an increasingly important role in materials science and condensed matter physics. This award provides partial support for the acquisition of a nearly unique high-magnetic-field/low-temperature facility to be operated at one of the Nations's major synchrotron X-ray sources, the Stanford Synchrotron Radiation Laboratory (SSRL). This new facility will allow the study of structural and magnetic properties of novel materials with the high momentum-resolution unique to synchrotron-generated X-rays, at magnetic fields up to 13 Tesla, and over more than three orders of magnitude in temperature, 0.3K T 400K.The scientific program involves the study of materials in which electron-electron interactions play an important role. Such "correlated-electron" materials are at the frontier of condensed matter physics, and they provide myriad possibilities to discover, observe, and characterize nove fundamental phenomena. For example, the strong electron-electron correlations in charge-carrier-doped antiferromagnetic insulators with perovskite-derived structures are known to lead to such diverse properties as: (i) insulator-metal transitions, (ii) high-temperature superconductivity, (iii) colossal magnetoresistance, (iv) charge-ordered phases, (v) and spin-ordered phases. The structural, magnetic, and electronic properties are generally intimately coupled in these systems, and the presence of a magnetic field often leads to new phases. The scientific program involves charge, resonant magnetic, and non-resonant magnetic X-ray scattering techniques. It will furthermore involve in situ transport measurements to obtain simultaneous structural, magnetic, and electronic information. Moreover, it will benefit from complementary research involving the growth and characterization of single crystals, neutron scattering experiments, and the collaboration with the ongoing photoemission spectroscopy effort at Stanford. This new high-magnetic-field/low-temperature synchrotron X-ray facility will thus allow the invesitgator to conduct research at the forefront of materials science and condensed matter physics, and it will help educate a new generation of undergraduate and graduate students with materials science, applied science, and physics backgrounds.%%%***