Basically I measure CP vs T at oT and 5T . And I want to separate out the lattice magnetic contribution using debye fit analysis using origin.
Why don't you just interpolate your two data sets and subtract them? This way you don't have to make any model assumptions about the lattice. You simply get rid of the field independent contribution to the heat capacity which originates from the lattice. Also if you want to apply the Debye model, keep in mind that the Debye model is typically written down for C_V vs T. You have to convert your C_P data to C_V data to apply the standard Debye model.The conversion can be done if you know bulk modulus and thermal expansion.
In general the total specific heat of magnetic materials in zero magnetic field can be written as: Cp=Ce + Cl + Cm where Ce, Cl and Cm represent the electronic, lattice and magnetic terms. This equation can be written as Cp= γT+βT^3 + αT^m.
The value of m depends on the magnetic state of your sample (para- ferro-, antiferro- magnetic or spin glass etc..).
For non magnetic and non conductor at low temperatures you can fit your data to Cp= β T^3 to estimate the value of Debye temperature, Ɵ.
For conductor and non magnetic you can estimate γ and β from the plot of Cp/T versus T^2. the intercept with the y-axis equals the electronic specific heat coefficient, γ and the slope equals β.
For the magnetic materials you have to determine the magnetic state of your sample first, is it para-, ferro- antiferro- magnetic ,etc?.. and what is the value of the critical temperature Tc or TN. For the paramagnetic materials try to fit the low temperature to the electronic and lattice terms to get an approximate idea about how strong is the magnetic state. For the antiferromagnetic the temperature exponent is 3 so that you have problem in separating the terms 2 and 3 from each other. For ferromagnetic materials try to use use m=3/2.
The best way is to use the specific heat of a similar but not magnetic materials and consider its specific heat as an acceptable representative of the nonmagnetic parts of the specific heat.
Try to read the paper: J. A. Morrison and D.M.T.Newsham J. Phys. C.Vol.1 (1968) 370-377. Which is attached. Good Luck.
Thank you very much sir...for your help.The TN of my sample is 48 K and it is ferrimagnetic material.
Have u got the answer to your problem if yes then kindly let me know or we can discuss.
With the help of origin you can easily do this, try to fit debye model above 50 K. Once you have got good fit of lattice part in above mentioned range, fix all parameters and change the data range to whole scan. Residual of the data will give you magnetic contribution.
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