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AC Chi

This document describes an experiment to measure the AC susceptibility and magnetic transitions of terbium metal powder. The experimental setup includes a lock-in amplifier, AC susceptibility coil setup, and the terbium sample. The experiment varies the AC voltage and frequency applied to the sample while measuring the output from the lock-in amplifier. It also varies the temperature to determine the magnetic transitions of the sample. AC susceptibility provides information about the magnitude and phase of the sample's magnetic moment and magnetization dynamics in response to an applied AC magnetic field.

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Brandon Stephens
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60 views2 pages

AC Chi

This document describes an experiment to measure the AC susceptibility and magnetic transitions of terbium metal powder. The experimental setup includes a lock-in amplifier, AC susceptibility coil setup, and the terbium sample. The experiment varies the AC voltage and frequency applied to the sample while measuring the output from the lock-in amplifier. It also varies the temperature to determine the magnetic transitions of the sample. AC susceptibility provides information about the magnitude and phase of the sample's magnetic moment and magnetization dynamics in response to an applied AC magnetic field.

Uploaded by

Brandon Stephens
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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AC Susceptibility

Aim

To find the susceptibility and magnetic transitions of the given magnetic material.

Apparatus Required

Lock in amplifier, AC Susceptibility coil setup, Material (Terbium metal powder)

Experimental Setup

Experimental Procedure

Load the given sample in the sample holder which fills exactly one of the secondary coil.
For a given frequency of 33 Hz vary the input AC voltage and observe the X and Y outputs
from Lock in Amplifier.
For a given applied AC voltage and frequency vary temperature and find the magnetic transition
of the given sample.
Working Principle

An AC magnetic field is applied to a magnetic sample and the resulting AC magnetic moment
is measured.

Measured AC susceptibility has two parts

= ' - i''
' - gives the information about the magnitude of magnetic moment
'' - gives the information about the phase dependence susceptibility

The induced sample moment is time-dependent, AC measurements yield information about


magnetization dynamics

AC susceptibility is also known as differential susceptibility and is defined as


dM
ac =
dH

Data and Analysis

X Output voltage of the Lock in amplifier gives corresponding ' value


Y Output voltage of the Lock in amplifier gives corresponding '' value

The net output voltage is the potential difference between the two secondary coils.
dH
V = e1 e2= f NA
0 ac
dt

Where H = H 0 e it

Finally the equation becomes V = i H 0 NA0 f ac

From the above equation we calculate the susceptibility. Also plot (i) ' vs. field as well as temperature
(ii) '' vs. field as well as temperature

Reference

Magnetic susceptibility of superconductors and other spin systems by Thomas.L.Fracavilla,


Donald H. Liebenberg

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