MRI: Acquisition of a High Field, Multi-Probe Cryogenic System for Quantum and Nano-Structured Materials Research

技术摘要：该项目将在约翰霍普金斯大学(JHU)建立一个用于凝聚态物理和纳米结构材料研究的强磁场、多探头低温设备。物理特性测量系统(PPMS)将提供从0到14特斯拉的四个数量级的温度(0.1K到1000K)和磁场的访问。测量能力包括比热、电和热传输、磁化和磁化率。为了确保可靠的长期运行，小型氦液化器将成为该系统的组成部分。PPMS将实现广泛的凝聚态物理和材料科学：将使用比热和磁化率测量来探索受挫量子磁体的低温高场相图和相应相变的临界性质。该仪器将被用来比较静态热力学参数与通过时间域太赫兹光谱和中子散射测量的强关联金属的互补动态性质。磁阻将被用来获得横向结构和有机半导体纳米结构中的自旋输运，以及具有微米级孔阵列的金属薄膜中的异常输运。磁化测量将用于探测纳米磁体和超导纳米结构。热输运测量将探测绝缘体/超导体边界上的量子相变。这样的测量还将作为热电应用的新型有机半导体材料的基准。JHU和我们的NSF-PREM合作伙伴霍华德大学的研究人员将能够通过高级实验室课程访问该仪器，JHU的大四学生和研究生也可以使用该仪器。该工具还将为与MRSEC相关的推广计划提供新的机会。非技术摘要：为了了解新材料的原子尺度性质并评估其在技术应用中的实用性，有必要在温度和外加磁场的精确控制条件下测量它们的物理性质。该项目将建立一个用于这种测量的设施，以补充约翰·霍普金斯大学与材料相关的广泛科学计划。物理特性测量系统将使材料承受从0.1K(-459.5华氏度)到1000K(1340F)的温度和高达14特斯拉的磁场(400,000倍于地球的S磁场)。在这些条件下，该仪器将能够探测材料的比热、电阻率、热导率和感应磁化，这些都挑战了我们对固体的基本理解，或为技术应用提供了新的可能性。例如，材料在强磁场中的电阻率揭示了电子电荷和电子自旋在材料中传输的复杂细节。这样的测量将被用来促进我们对有机半导体的理解，这些有机半导体具有在塑料电子中的应用潜力。同样，样品的场致磁化揭示了其磁结构的细节。这种测量将被用来评估具有在超高密度信息存储系统中应用的潜力的纳米工程结构。在所谓的受挫磁铁中，由竞争相互作用引起的物质的新状态？以及所谓的强关联金属中的电子相互作用？将通过比热和磁化测量来探索。最后，热传输测量将用于探索有助于解决能源挑战的新型热电材料。PPMS还将成为约翰·霍普金斯大学广泛的本科生、研究生和教育外展项目的组成部分，并得到加强。

Technical abstract: This project will establish a high-magnetic-field, multi-probe cryogenic facility for condensed matter physics and nanostructured materials research at Johns Hopkins University (JHU). The Physical Properties Measurement System (PPMS) will provide access to four orders of magnitude in temperature (0.1 K to 1000 K) and magnetic field from 0-14 Tesla. Measurement capabilities include specific heat, electrical and thermal transport, magnetization, and magnetic susceptibility. To ensure reliable long term operations, a small helium liquefier will be an integral part of the system. The PPMS will enable a broad range of condensed matter physics and materials science: Specific heat and magnetic susceptibility measurements will be used to explore the low temperature high field phase diagram of frustrated quantum magnets and the critical properties of the corresponding phase transitions. The instrument will be used to compare static thermodynamic quantities to the complementary dynamic properties of strongly correlated metals measured through time-domain THz spectroscopy and neutron scattering. Magneto-resistance will be used to access spin transport in lateral structures and organic semiconductor nano-structures and anomalous transport in metallic thin films with arrays of micron sized holes. Magnetization measurements will be used to probe nano-magnets and superconducting nano-structures. Thermal transport measurements will probe quantum phase transitions at the insulator/superconductor boundary. Such measurements will also benchmark novel organic seminconducting materials for thermoelectric applications. Researchers throughout JHU and from our NSF-PREM partner Howard University will be able to access the instrument as will JHU seniors and graduate students through advanced laboratory courses. The instrument will also provide new opportunities for MRSEC related outreach programs. Non-technical Abstract: To understand atomic scale properties of new materials and access their utility for technical applications it is necessary to measure their physical properties under accurately controlled conditions of temperature and applied magnetic field. This project will establish a facility for such measurements to complement a wide range of materials related scientific programs at the Johns Hopkins University. The Physical Properties Measurement System (PPMS) will subject materials to temperature from 0.1 Kelvin (-459.5 F) to 1000 K (1340 F) and magnetic fields up to 14 Tesla (400,000 times the earth?s field). Under these conditions the instrument will be able to probe the specific heat, the electrical resistivity, the thermal conductivity, and the induced magnetization of materials that challenge our basic understanding of solids or present new possibilities for technical applications. The electrical resistivity of materials in high magnetic fields for example reveals intricate details of electron charge and electron spin transport through the material. Such measurements will be used to advance our understanding of organic semiconductors with potential for applications in plastic electronics. Likewise the field induced magnetization of samples reveals details about their magnetic configuration. Such measurements will be used to evaluate nano-engineered structures with potential for applications in ultra high density information storage systems. New states of matter induced by competing interactions in so-called ?frustrated magnets? and by electron interactions in so-called ?strongly correlated metals? will be explored through specific heat and magnetization measurements. Finally, thermal transport measurements will be used to probe novel thermoelectric materials that can help to address the energy challenge. The PPMS will also become an integral part of and strengthen a wide range of undergraduate, graduate, and education outreach programs at Johns Hopkins University.