I am looking at confirming the presence of magnetoelectric coupling in doped-BTO thin films. I have confirmed the presence of ferroelectricity and ferromagnetism independently using the triangular waveform voltage and SQUID magnetometry.
To confirm the magnetoelectric effect, all I need to do is perform standard C-V measurements, with and without a magnetic field, and note any change in capacitance, according to the linked journal.
I have the capacity to perform C-V measurements using a Keithy semiconducter analyser, however I don't have the ability to performing the probing with and without the magnetic field.
Can anyone recommend how to best perform these measurements? Is there a probing station capable of performing these measurements, or is there an affordable way to make my own DIY probing apparatus?
Best wishes
David Coathup
http://iopscience.iop.org/article/10.1088/0022-3727/46/42/425001
With NdFeB permanent magnets you can reach 1T. By putting your sample between a pair of such magnets and varying the distance between them you can even adjust the field. The biggest problem would be to calibrate the setup. For that you would need a Hall probe or similar.
Dear Dr. Detlefs,
Thank you for your feedback. Could you elaborate on your point about 'calibrating the set up'. To my understanding, the measurements can simply be performed using a standard semiconductor analyse, To measure the the C-V relationship. with and without the magnetic field.
Calibrate in the sense that you probably want to know how strong the magnetic field is at what spacing of the magnets. Once you have set up the magnets, the C-V measurement is the same as without magnets.
Dear David Coathup,
you can use magnet to produce 1 T with high stability of field. But as mentioned by Dr. Detlefs, you need to know how strong the field with respect to the distance between magnet and the point of measurement. A bigger area of magnet may produce a better uniformity of field.
I have designed a magnetoelectric setup capable of measuring ferroelectric properties (C-V, P-E, I-V…) at different temperatures (77-500 K) under applied magnetic field (up to 1 T). The magnetic field is produced by a custom-developed magnet. Our electromagnet contains two copper coils, and soft iron in their core to focus the magnetic flux on the sample position. One of the coils is mounted on a rail so as it can be shifted to modify the spacing between the two magnetic poles. The magnet is controlled with a bipolar power supply (properly chosen to fit the characteristics of the coils). All sample fixtures are made of nonmagnetic materials. A Gaussmeter fixed close to the sample position displays the magnetic field value. Note that this instrument is meant for static measurements, i.e., the magnetic field is swept at low-frequency.
Glad to share our experience with you and best of luck for your experiment.
You can use Halbach arrangement to produce 1T with reasonable uniformity. As other commentators suggest, use Hall probes to make sure the field has the characteristics suited for your purpose. Shim coils can be used to make the field more uniform.
Hope this helps.
David Coathup
Did you ever get your magnet working? I am writing notes on magnetic calculations and your 1 Tesla magnet is a good problem. This morning I found a good example in "Electromagnetics" by John D Kraus and Keith R Carver, 2nd Edition 1973, page 250. They cover magnetization in the previous pages, including hysteresis, units and relationships. Their example used a soft iron toroid. Its length 600 mm and diameter about 35.7 mm. For 1 Tesla, the magnetic permeability is 1000 mu0. With a length of 0.6 meters, they need 600 amperes turns per meter. They considered 1000 turns of 0.6 Amperes, and 100 turns of 6 Amperes. But with pulsed drone electronic speed controllers and stepper motor controllers now, they might well have considered pulsed 60 Amperes and 10 turns or a smaller device. With synchronized measurements and faster ADCs short pulses or arbitrary signals are workable.
Think of an 1.4 inch rod, 24 inches long, bent into a circle. If you don't close it, the field in the gap should be close to 1 Tesla.
A lot is happening in magnetics. Too much to put into another paper book. So I am trying to find a way to share and collaborate online, so that many people can add things they know - in a consistent framework. So that knowledge is immediately applicable, rather than ending up in piles of useless facts and fragments on paper or in PDFs or old websites.
You might be like many people, and only care about this kind of thing for a short while. But I was wondering if you stayed at magnetics? Or things related?
Richard Collins, The Internet Foundation
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