Examining Electrical Transport Properties at Cryogenic Temperatures with the attoTMS

Interview conducted by Zoe PeterkinOct 9 2018

Florian Otto, head of product management at attocube systems, talks to AZoM about the new attoTMS transport measurement solution for experts. It not only allows to fully automate complex transport measurements in any parameter, but also provides a 9T full rotating vector field on the sample.

Please could you introduce the attoTMS system to our readers?

The attoTMS is a fully programmable measurement platform, used for investigating electrical transport properties of samples and devices at cryogenic temperatures and in high magnetic fields. Such electrical characterization via magnetotransport measurements is amongst the most common tools in fundamental physics and materials science research.

How does the attoTMS system assist with magneto-transport measurements?

Typically, there have been two different approaches to magnetotransport measurements. Either you are an expert, and configure and set up your experiment all by yourself; usually involving components from many different suppliers. While this results in maximum flexibility, it also implies tremendous amounts of work for PhD students and postdocs, to actually interface all those different instruments. Most magnetotransport measurements consist of a multidimensional explorations of a large phase space, by varying many physical parameters; such as temperature, magnetic field strength and direction, gate voltages, bias voltages, etc. This requires sophisticated software routines, which are often completely rewritten by every generation of PhD students in every lab.

The other approach is to buy a fully automated measurement system, which can be operated even by beginners. However, this usually comes at the cost of working with a black box, which has very limited capabilities to begin with, and very little flexibility for changes in the measurement routine by the user.

The attoTMS combines the best of both worlds, by offering an expert platform that has an enormous amount of features and flexibility, even via scripting, yet still integrates all of the essential hardware into one single user interface. This allows for straightforward automation of even elaborate measurement schemes, and hence provides a powerful turnkey solution, without compromises on versatility.

Could you please tell us about the different aspects that make up the attoTMS - the attoDRY2100, Nanonis Tramea™ and atto3DR?

The measurement platform consists of the attoDRY2100, an automated closed-cycle cryostat, the atto3DR, an in-situ double rotator sample stage, and the extremely powerful all-in-one measurement electronics Nanonis Tramea™.

The cryostat liberates the user from liquid helium, and can automatically access temperatures anywhere between 1.65 to 300 K. At the same time, it allows for the full magnetic field (e.g. 9 T or 12 T) even at a sample temperature of 300 K; thus allowing for field cooling, i.e. cooling down a sample in a high magnetic field. The cryostat features a convenient touchscreen interface for temperature and magnetic field control, plus other parameters, but can of course also be remote controlled via the Tramea software.

The atto3DR double rotator stage provides the unique possibility to access the full magnetic field (e.g. 9 T) in 3D – stronger and faster than any vector magnet – by rotating the sample, and not the magnet. It also features a 20 pin chip carrier for fast sample exchange.

The Nanonis Tramea™ on the other hand replaces a full rack of conventional measurement equipment, such as voltage sources, DC voltmeters, lock-in amplifiers and even function generators, in one single box. It features up to 40 analog outputs, and up to 24 analog inputs, which can be configured within the software to represent any desired experimental channel, i.e. signal source or measurement. This basically removes the need to physically re-wire your sample, since it allows for switching between wiring schemes digitally, and it also reduces the likelihood of ground loops.

What features make the attoTMS unique in the marketplace?

Some features are completely new, such as the precise and remote controlled in-situ double rotator, which allows you to access arbitrary 3-dimensional vector fields more easily and with higher field strength than is possible in conventional setups. The same holds for the concept of the Nanonis Tramea™, which not only combines the capabilities of a multitude of other electronics in one box, but is also both high speed and high signal performance: it offers similar or better performance than dedicated DC sources or multimeters and at the same time up to 1000x higher measurement speed.

However, the most important feature of the attoTMS is the combination of all of these outstanding features in one complete package. The software seamlessly integrates the control of all relevant parameters, such as temperature, magnetic field strength and direction (by controlling the sample orientation), and any other electrical parameters. Investigating your complete physical phase space was never easier!

How does the attoTMS system help to overcome challenges in the field?

Many transport measurements involve time-consuming, multi-dimensional parameter sweeps. These measurements used to be cumbersome to set up, because in every lab there were and still are home-written routines to enable automation of such tasks, and could last for several days. The speed-up possible with the Tramea can be tremendous: a typical measurement of the Conductance of a nanodevice routinely takes several hours to a full day using conventional measurement equipment. With the Tramea, an even better set of data can be acquired in less than an hour and a quick overview of the device with less resolution in a couple of minutes.

Combine that with the ability to set up an automated measurement at many different temperatures, and magnetic fields strengths and potentially different orientations (e.g. for nanowires), and it becomes obvious that the attoTMS represents a solution superior to anything that was previously available.

About Florian Otto

Dr. Florian Otto is the Head of Product Management at attocube systems. His role involves market evaluation & projection, competitor surveillance, portfolio management, roadmapping and strategic product positioning. He has been with attocube systems since 2009, previously holding positions as a technical sales engineer and as product manager for attocube’s microscope and cryostat portfolio. Prior to joining attocube, he completed a PhD in Physics at the University of Regensburg, studying nonlocal effects in vortex dynamics in conventional superconductors via transport measurements.