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NPL’s quantum capabilities for industry

Magnetic and electrical transport properties of materials and devices

Analysis of magnetic and electrical transport properties of low loss electronic materials and devices

The analysis of magnetic and electrical transport properties is a rapidly growing field with a wide range of applications such as low loss electronics, sensors or future compute components. Our tests can be run in extreme environments at a temperature and magnetic field range of 1.8K-400K and 0T-9T respectively. There are many reasons why someone might need an analysis of the magnetic and electrical transport properties of materials and devices in a controlled environment. Here are a few examples:

  • To design new materials and devices with improved properties. By understanding the fundamental properties of materials, scientists and engineers can design new materials and devices with specific properties that are desired for a particular application. For example, materials with high electrical conductivity can be used to make wires and cables, while materials with high magnetic permeability can be used to make magnets.
  • To improve the performance of existing materials and devices. Even materials and devices that are already in use can often be improved by understanding their magnetic and electrical transport properties. For example, by understanding how the conductivity of a material changes with temperature, engineers can design devices that are more efficient at operating in cold environments.
  • To study the fundamental physics of magnetism and transport. The analysis of magnetic and electrical transport properties can also be used to study the fundamental physics of magnetism and transport. For example, by studying how the conductivity of a material changes in the presence of a magnetic field, scientists can learn more about the interaction between electrons and magnetism.

NPL can offer analysis of the magnetic and electrical transport properties of materials and devices in a controlled environment. The magnetic field and temperature can be precisely controlled, and the analysis can be performed on bulk, thin film, powder samples and electronic devices.

This capability would be of interest to those working on next generation low loss electronics.

The system at NPL is designed to measure the physical properties of materials in a variety of forms. A requirement is that the sample is small enough to fit within the measurement volume of the instrument.

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Here are some of the benefits of NPL's analysis capability:

  • Precise control of the magnetic field and temperature: This allows for accurate measurements of the magnetic and electrical properties of materials and devices.

  • Ability to measure bulk, thin film, and powder samples: This allows for a wide range of materials to be analysed.

  • Experienced staff: NPL's staff has extensive experience in measuring the physical properties of materials and devices.

Magnetometry

NPL can use a Vibrating Sample Magnetometer (VSM) to measure a sample's magnetic moment as a function of temperature or magnetic field. The VSM is a fast, sensitive, and fully automated DC magnetometer. It works by oscillating the sample in a pickup coil and synchronously detecting the induced voltage.

The VSM uses a compact gradiometer pickup coil configuration, a relatively large oscillation amplitude (1-3 mm peak), and a frequency of 40 Hz. This allows the system to resolve magnetization changes of less than 10-6 emu at a data rate of 1 Hz.

Due to the size of the pickup coil, samples are currently limited to diameters and lengths of less than 4.5 mm and 5 mm, respectively. The diameter is physically limited by the bore of the pickup coil, while lengths in excess of 5 mm tend to produce a reduced moment that is best to avoid. Samples are mounted to either quartz paddles or brass troughs, as required.

Here are some of the benefits of using a VSM:

  • Fast: The VSM can measure magnetic moments quickly, which is important for studying materials that change their magnetic properties over time.
  • Sensitive: The VSM can detect very small changes in magnetic moment, which is important for studying materials with weak magnetic properties.
  • Fully automated: The VSM is fully automated, which means that it can run measurements without any user intervention. This frees up the user to focus on other tasks, such as preparing samples or analysing data.

Electrical transport

Electrical transport measurements are typically limited to samples that are less than 10 mm x 10 mm in lateral extent and several millimetres in thickness. Powders are typically pressed into geometries (sometimes with the aid of binders) that satisfy these dimensional requirements. The currently available measurement options are:

  • DC resistivity: This can be done in either 2- or 4-wire mode. 4-wire mode is preferred, as it greatly reduces the contributions from lead and contact resistances.
  • ACtransport: This can be used to measure a variety of electrical properties, such as conductivity, resistivity, and Hall coefficient.
  • Multi-function probe: This can be used to measure a variety of properties, including electrical transport and magnetic properties.

Within the approximately 10 mm x 10 mm mounting area within the instrument, there is typically room for up to 3 samples, provided they are sized appropriately.

The Electrical Transport Option (ETO) enables AC electrical transport measurements of samples using a 2- or 4-probe lead configuration. The 2-probe configuration is suitable for all ranges of samples, while the 4-probe configuration is especially useful for looking at resistive samples, or those where pulsed current measurements could be utilized such as when studying memristors.

The 4-probe configuration is advantageous in terms of reducing the contribution of lead and contact resistances. With proper lead placement, the Hall coefficient can also be measured in 4-wire mode.

In addition to resistance and Hall coefficient, 2- and 4-wire current-voltage curves as well as differential resistance (dV/dI) can be measured. In 4-wire mode, the voltage response is measured in response to a current excitation. In 2-wire mode, the current response is measured in response to a voltage excitation.

The DC resistance option allows for resistance measurements on up to three channels using a standard puck. This option highlights the efficiency of the system, as it allows for full temperature and field sweeps of three samples to be taken simultaneously, reducing the time cost even further.

Here are some of the benefits of using the DC resistance option:

  • Efficiency: The ability to measure three samples simultaneously reduces the time required to complete a measurement.
  • Accuracy: The use of a standard puck ensures that the measurements are accurate and reproducible.
  • Flexibility: The ability to measure resistance on up to three channels allows for a wide range of materials and devices to be studied.

Are you interested in learning more about our quantum capabilities?

Contact a member of NPL's quantum team today to schedule a consultation. We can discuss your specific needs and how our quantum technologies can help you achieve your goals.

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