Wimbush提供物理特性测量系统 (PPMS) 提供一系列经过实验室验证的独特创新配件。 我们的核心产品最初是在德国的一个研究实验室开发的，并在那里和世界各地日常使用。

PPMS附件产品咨询：伽太科技，185 0219 3480

压接组件

• Van der Pauw 压接组件

• 转子压接组件

旋转样品架

接线盒

• BNC接线盒

• 定制贴片盒

基于 PPMS 的范德堡测量

测量软件

• 测电软件

• 介电测量软件

• 超导体测量软件

利用我们使用 PPMS 仪器进行测量的丰富经验，我们还可以为您的特定测量挑战定制设计创新且具有成本效益的解决方案。

Press Contact Assemblies

We have developed a range of press contact assemblies facilitating the rapid and easy mounting of samples for electrical measurement using the Physical Property Measurement System (PPMS) of Quantum Design. With these press contacts, samples can be prepared for measurement in seconds rather than hours.

The assemblies are designed to work with the PPMS resistivity, ac transport or electrical transport measurement options. For four-point electrical measurement, the contacts are aligned linearly, with a 2 mm pitch (see detailed schematic). Samples up to 4 mm in thickness can be accommodated, so long as they can rest stably on the puck surface. Resistivity, IV curve and critical current measurement are all supported (dependent on the installed measurement option). Hall effect measurement requires a different contact arrangement, also available.

Utilising our extensive experience of measurement using the PPMS instrument, we are also able to custom-design press contact assemblies to address your particular measurement challenges. Contact us for more information, or view the detailed schematic for some of our more common alternative layouts.

These assemblies have been making our lives easier in our research laboratories in Germany for over ten years, and are now in use in laboratories around the world. Examples of the types of samples able to be successfully measured are shown in the photographs to the side. Both thin film and bulk samples can be accommodated.

Electrical Transport Option

The new electrical transport measurement option utilises standard resistivity option pucks, and as such any of our press contact assemblies designed for use with the resistivity option will also work with the ETO. Important to note, however, is that only measurement channels 1 and 2 are passed through to the ETO, even though channel 3 remains present.

Van der Pauw Press Contact Assemblies

PPMS Application Note 1076-304 describes a method of performing van der Pauw resistivity measurements on samples of arbitrary geometry. Such measurements are ideally suited to a rapid, hassle-free press contact setup, and we have developed assemblies to facilitate this. Using these, all the connections described in the Application Note are neatly and correctly implemented, leaving the user free to simply acquire and process the data. By selecting appropriate pin positions, a single assembly can support samples of multiple sizes: as standard, contact points spaced 2×2, 4×4, 6×6, and 8×8 mm are available to choose from. Custom arrangements are also available — simply contact us for details.

Note that reversed polarity measurements are trivially implemented in the measurement sequence as a means of improving accuracy through the elimination of offset voltages. A further improvement can be achieved by compensating for geometrical effects by additionally making reciprocal measurements; however since only three PPMS measurement channels are available, this requires the incorporation of a switch system, for example utilising our van der Pauw patch box to provide access to the PPMS measurement lines to reverse the contacts during measurement. More specific details of the measurement procedure are available here.

Van der Pauw Hall effect measurements are also possible in principle. However, the time taken to reverse the polarity of the applied field between measurements can lead to unsatisfactory results. We are presently working on developing the possibility to conduct these measurements in the PPMS rotator, thereby enabling the sample to be rotated quickly through 180° rather than reversing the field.

The press contact assemblies must be mounted onto an existing puck of the appropriate PPMS option (resistivity or ac transport). This requires a (fully reversible) modification of the puck to be made, which is quite straightforward. Easy-to-follow instructions are available here. Replacement spring-loaded probe tips are available in the event that one becomes fatigued, damaged or contaminated. These are easily user-exchangeable.

Rotator Sample Mounts

Our rotator sample mounts are designed to be drop-in alternatives to those available from Quantum Design, with the added advantages of full support across the range for sample sizes up to 10 × 10 mm, as well as rear-side electrical pathway routing to reduce the likelihood of damage when contacting or removing samples, eliminated thermocouple contact pads to prevent accidental shorting, and standardised contact pad positioning for both resistivity and ac transport options. Available from stock in common configurations, we can also custom design a solution appropriate to your particular measurement requirements — contact us for details.

Our van der Pauw rotator sample mounts offer the same benefits to the rotator as our van der Pauw puck overlays offer the standard measurement pucks, while if you perform frequent rotator measurements, you may find our rotator press contact assemblies useful.

PPMS-based van der Pauw Measurements

We are the leading supplier of PPMS van der Pauw measurement solutions.

Our van der Pauw press contact assemblies make PPMS-based van der Pauw measurements of sample resistivity or Hall coefficient a breeze, correctly routing the three channels of the resistivity option or the two channels of the ac transport option to the appropriate geometry on the sample, as shown in the “normal” column of the figure to the right. Alternatively, a manually contacted sample can be set up for measurement in the same way using one of our patch boxes.

For those who wish to dedicate a sample puck to van der Pauw measurements without the use of press contacts, our van der Pauw puck overlays (below) route the appropriate connections of the available measurement channels to conveniently arranged contact areas on the puck, while providing the largest possible sample area (suitable for samples up to 13 × 13 mm) on the puck surface. Our van der Pauw rotator sample mounts provide the same functionality to the PPMS rotator.

PPMS Application Note 1076-304 describes the use of the PPMS instrument for making van der Pauw measurements. A more detailed description of the method is available from NIST. In particular, note that reverse polarity measurements are easily implemented in the measurement sequence thanks to the bipolar capability of the Model 6000 / Model 7100 current source.

However, a rigorous van der Pauw measurement requires the incorporation of both reverse polarity and reciprocal measurements, to cancel out erroneous effects due to an imperfectly symmetrical sample geometry. Reciprocal measurements are not so easily performed since they require alternation of the contacts, as shown in the “reciprocal” column of the figure. Our van der Pauw patch box enables this to be done manually via a set of front panel switches during measurement, without the need to remove and remount the sample.

Note that our puck overlays are supplied as boards only. These must be attached to a bare puck and twelve wires soldered between the contact points on the board and the contact areas on the underside of the puck.

HTS wire critical current database

We believe that the greatest contemporary impediment to the broader industrial uptake of high temperature superconducting technologies is a lack of detailed performance data on the commercially available wires. While wire manufacturers continue to supply minimal characterisation data on their products, often at only a single, largely irrelevant temperature, efficient use of the wire is rendered impossible, resulting in machine and device designs that are both uneconomical and that fail to take full advantage of the benefits (in terms of size, weight and performance) that superconductivity provides.

The database linked via the image below is an attempt to remedy this situation. It provides detailed critical current characterisation data for superconducting wires sourced from many of the prominent manufacturers in a form that it is hoped will enable optimisation of the design of superconducting machines and devices, and thereby spur the uptake and further cost reduction of high temperature superconducting technologies. An interactive interface enables convenient online browsing of the underlying data files.

The database is completely free to access, with the data offered under a Creative Commons Attribution (CC-BY) licence, providing minimal restriction to reuse. It is intended that the database will remain current and will be updated and expanded regularly.