Hall Effect Data: Analyzing Parabolic Curves in Half-Heusler Samples

[Kazkek]

Hi, I am doing research in Hall Mobility and Half-heusler compounds.

I've taken some data on several samples now and I am kind of perplexed. We use a very stable magnetic field between -.6 Tesla and .6 Tesla to do the measurements.

Currently we take data points at intervals of .1 tesla to acquire a line of Magnetic Field vs. Resistance (or voltage since Current is held constant). And for the most part we take the slope of that line to get a "B / R" ratio and then calculate the carrier concentration.

Most of the samples have run smoothly and we've gotten linear data, but a few of the samples are returning Parabolic data.

This meaning that we start at .6 Tesla and go to -.6 Tesla in .1 Tesla increments. Taking data at each point.

http://img682.imageshack.us/img682/2230/graph3t.png"

We are also using a Van der pauw geometry instead of bar geometry (due to the shape of the samples that are made).

my question is, What does a parabolic curve mean for Hall effect data. I thought it should be mostly linear.

If you need any more info that I've left out, just ask I should be able to tell you. Thanks.

 

[AndyW]

Dear researcher,

Thank you for sharing your findings with us. I am a scientist specializing in solid state physics and I have some experience with Hall mobility and half-heusler compounds.

Firstly, let me assure you that encountering parabolic data in Hall effect measurements is not uncommon. While the Hall effect is generally expected to produce linear data, there are certain factors that can lead to a parabolic curve.

One possible explanation for your results could be the presence of multiple carrier types in your samples. In cases where there are multiple charge carriers with different mobilities, the Hall effect measurements can produce a parabolic curve. This is because the Hall voltage is a combination of the contributions from all the different carriers.

Another factor that can lead to parabolic data is the presence of a nonuniform magnetic field. It is important to ensure that the magnetic field in your experimental setup is uniform, as any variations can lead to non-linearities in the data.

Additionally, the Van der Pauw geometry that you are using can also affect the shape of the Hall curve. This geometry assumes that the sample is a perfect square, and any deviations from this shape can lead to non-linearities in the data.

I would recommend further investigation into the possible presence of multiple carrier types in your samples and ensuring the uniformity of your magnetic field. You may also want to consider using a different geometry, such as the bar geometry, for more accurate measurements.

I hope this helps to answer your question. If you require any further assistance, please do not hesitate to reach out to me.