A Scanning Hall Probe Microscope for High Resolution milliKelvin Magnetic Imaging

用于高分辨率毫开尔文磁成像的扫描霍尔探针显微镜

基本信息

批准号：
EP/D034264/1
负责人：
Simon Bending
金额：
$ 34.16万
依托单位：
University of Bath
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2006
资助国家：
英国
起止时间：
2006 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FD034264%2F1
关键词：
Scanning Hall Probe Microscope Resolution

项目摘要

Some of the most exciting contemporary problems in condensed matter physics are in the area of nanoscale quantum mechanics and relate to the properties of superconducting and ferromagnetic materials at ultra-low temperatures, e.g. in the study of macroscopic quantum tunnelling and novel forms of quantum order. A key aspect of this work is the ability to perform high spatial resolution magnetic imaging down to ultra-low temperatures and/or at high magnetic fields. Due to the major technical challenges posed in these regimes, no magnetic imaging system currently exists which is capable of nanoscale imaging. Over the last decade we have successfully developed a number of scanning Hall probe microscopes (SHPMs) in Bath which span the temperature range 4.2-300K. These Hall probe systems represent a very flexible approach to magnetic imaging since Hall sensors can readily be fabricated with ~100nm spatial resolution and excellent minimum detectable fields and, using high probe current densities, can be operated in magnetic fields of several Teslas. All existing SHPM systems use 4He exchange gas cooling and, hence, can only be operated above 4.2K. In order to address a range of exciting contemporary problems in magnetic materials at much lower temperatures we propose to design and construct a new SHPM head which can be directly attached to the 300mK cold pot of a commercial 3He cryostat insert. This instrument will be capable of operation in magnetic fields up to 10T with a spatial resolution >100nm and minimum detectable field ~10mG/Hz^0.5. Its unique properties will be exploited to open up a new front in the field of nanoscale quantum phenomena. Within the project we will search for novel vortex structures and spontaneously generated flux in the unconventional superconductor Sr2RuO4, and will attempt to establish the mechanism for macroscopic quantum tunnelling of the magnetisation in the molecular magnet Mn12-acetate. In addition we will search for new geometry-driven vortex structures in mesoscopic Al disks.

当代凝聚态物理中一些最令人兴奋的问题属于纳米级量子力学领域，并且与超导和铁磁材料在超低温下的特性有关，例如超导和铁磁材料。研究宏观量子隧道效应和量子秩序的新形式。这项工作的一个关键方面是能够在超低温和/或高磁场下执行高空间分辨率磁成像。由于这些领域提出的主要技术挑战，目前不存在能够进行纳米级成像的磁成像系统。在过去的十年中，我们在巴斯成功开发了多款扫描霍尔探针显微镜 (SHPM)，温度范围涵盖 4.2-300K。这些霍尔探针系统代表了一种非常灵活的磁成像方法，因为霍尔传感器可以很容易地制造成具有约 100 nm 的空间分辨率和出色的最小可检测场，并且使用高探针电流密度，可以在几个特斯拉的磁场中工作。所有现有的 SHPM 系统均采用 4He 交换气体冷却，因此只能在 4.2K 以上运行。为了在更低的温度下解决磁性材料中一系列令人兴奋的当代问题，我们建议设计和构造一种新的 SHPM 头，该头可以直接连接到商用 3He 低温恒温器插入件的 300mK 冷锅上。该仪器能够在高达 10T 的磁场中运行，空间分辨率 >100nm，最小可检测场 ~10mG/Hz^0.5。其独特的性质将被用来开辟纳米级量子现象领域的新前沿。在该项目中，我们将在非常规超导体 Sr2RuO4 中寻找新颖的涡流结构和自发产生的通量，并将尝试建立分子磁体 Mn12-醋酸盐中磁化的宏观量子隧道机制。此外，我们将在介观铝盘中寻找新的几何驱动涡流结构。