I have recently tried to measure precision low voltage measurement using Keithley nanovoltmeter with time varying magnetic field. But always getting false voltage varying with this increasing magnetic field.
Attached here my sample mounted on a copper base . Placed in between Electromagnet poles and connected with copper wires to a nanovoltmeter.
Hi Vinay,
could you additionally submit a schematic of the circuit you place between the poles, and both the result you expected (plus the way you arrived at it) and the result you've got?
From the picture alone, I'm not certain what you are measuring.
Joerg Fricke , i am measuring Spin pumping voltage which i suppose is already discussed in literature.... But i think measurement circuit is not a problem...i just want to know that what are the important things required to be kept in mind while measuring precision voltage in presence of time varying magnetic field?
Also, i have tried this by just putting two contacts on a bare platinum film and connected it to nanovoltmeter, and when magnetic field ramp increases, voltage in nanovoltmeter also increased. Even i have also tried bu just putting my nanovoltmeter connection leads in between electromagnet poles...and still i am getting some false voltage ...so what i am doing wrong????Is something special required for doing voltage measurement in presence of magnetic field?
I just found an article by Iguchi and Saitoh on this topic, but haven't read it yet.
However even without knowledge of the details, I suspect that you didn't took good old classical induction into account:
curl E = -d B / d t
which means that in every loop of wire a voltage is induced if a time varying magnetic field is reaching through the loop. You measured this voltage when you put the bare leads between the poles,
The remedy is using coax cable. Additionally, I guess you cannot avoid forming a small loop by the platinum film and the connections to the coax cable but you should care to have this loop so oriented that no magnetic field lines are crossing the plane of the loop, and you should keep the area of the loop as small as possible. With Cartesian coordinates projected into your picture, x axis pointing to the right, the plane of the loop should lie in an x-z-plane.
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