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

技术摘要：本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高磁场、多探针低温设备。物理特性测量系统（PPMS）将提供4个数量级的温度（0.1 K至1000 K）和0-14特斯拉的磁场。测量能力包括比热、电和热输运、磁化率和磁化率。为了确保可靠的长期运行，一个小型氦气液化器将是系统的一个组成部分。PPMS将实现广泛的凝聚态物理和材料科学：比热和磁化率测量将用于探索受挫量子磁体的低温高场相图和相应相变的关键特性。该仪器将用于比较静态热力学量和通过时域太赫兹光谱和中子散射测量的强相关金属的互补动态特性。磁电阻将用于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尺寸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/超导体边界处的量子相变。这样的测量也将为热电应用的新型有机半导体材料提供基准。JHU的研究人员和我们的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将能够使用该仪器。该仪器还将为MRSEC相关的外展计划提供新的机会。摘要：为了了解新材料的原子尺度性质并获得其技术应用价值，有必要在精确控制的温度和外加磁场条件下测量其物理性质。该项目将为此类测量建立一个设施，以补充约翰霍普金斯大学广泛的材料相关科学项目。物理特性测量系统（PPMS）将使材料承受0.1开尔文（-459.5华氏度）到1000 K（1340华氏度）的温度和高达14特斯拉（40万倍于地球磁场强度）的磁场。字段)。在这些条件下，该仪器将能够探测材料的比热、电阻率、导热率和感应磁化率，这些材料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材料中电子电荷和电子自旋输运的复杂细节。这样的测量将用于提高我们对有机半导体在塑料电子领域的应用潜力的理解。同样地，样品的磁场感应磁化揭示了它们的磁性结构的细节。这样的测量将被用来评估纳米工程结构在超高密度信息存储系统中的潜在应用。物质的新状态由所谓的？沮丧的磁铁吗?通过所谓的电子相互作用？强相关金属？将通过比热和磁化测量来探索。最后，热输运测量将用于探索有助于解决能源挑战的新型热电材料。PPMS也将成为约翰霍普金斯大学广泛的本科生、研究生和教育推广项目的一个组成部分，并加强这些项目。

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.