What do you mean by "calculate"? A theoretical approach? The determination based on some measurement(s)?

If the latter is the case then you need to specify what your experiment is, what your sample is and what you (really) know about your sample(s).

Only then do we know what to talk about and only then can proper advice be given.

Thank you Sir for your attention!

I want to calculate from the measured moment.

I have moment in emu/cc of a thin film of Ga1-xMnxAs and In1−xMnxAs with different x values (eg x=0.12).

I am trying to convert it into MuB/Mn ion.

OK. I guess that in fact you have a moment value (in emu) from a magnetometry measurement and that you (believe to) know the volume of the film from some other characterization of the thin film. Is that correct?

Furthermore you have some measure of the (nominal) composition of the GaMnAs film. Also correct?

If yes, then you can make an estimate of the per-Mn-moment by converting from emu to Bohr magnetons. For this you need to know what definition of emu is being used by your magnetometer (this is something I am not familiar with and on the web I find that in principle [at least] two different definitions might be possible). After what I read, it is likely that the definition being used is

1 emu = 10-3 J/T

At the same time we have

1 µB = 9.274×10−24 J/T

from which you obtain the total moments in Bohr magnetons (if you have measured the saturation moment of your sample at low temperature). Be careful, if you have a thin film, then your substrate will also contribute (likely a diamagnetic contribution, linear in the field) and it might be a delicate procedure to correct for that contribution with good accuracy.

What you now need to find out is the number of Mn sites in your film, based on its dimension (volume) and atomic density (lattice constant of GaAs as an approximation, maybe you have more accurate values from doing XRD on your films).

Finally: not all Mn sites need to be contributing: if the surface of the film is not protected, there will be extrinsic, paramagnetic sites (e.g. from surface oxidation). Their importance will be the smaller, the thicker your film. Note also that, depending on Mn concentration there may be pairs of Mn sites (called dimers in the literature) which are antiferromagnetically coupled and therefore - at the extreme limit - not contribute at all to the net moment. In that case the moment per Mn site you determine by the above procedure will be a lower limit to the magnetic moment of the magnetically active sites.

You may find some information on how "extrinsic" sites may contribute in our paper linked below. More importantly, search for publications of K. W. Edmonds et al. on the subject. It's been a while since I have been active on the subject and there might be much more knowledge available in the literature which may help to better interpret whatever you find. Keep track of the propagation of errors/uncertainties towards the moment you determine based on those of the (more or less well-) known quantities and the uncertainties involved in the evaluation of the magnetometric measurements!

Good luck.

Article Identification of extrinsic Mn contributions in Ga1−xMnxAs b...

Dear Sir,

Thank you for the explanation.

I have small doubt. During density calculation from the crystal structure data, one should consider no. of atoms per unit cell of no. of formula units per unit cell?

Some people say that z in the formula is no. of atoms per unit cell

while other say that z in the formula is  no. of formula units per unit cell

Formula is: density= M*z/(V*N)

please help me

Actually I don't know what "z" is meant to be. My approach would not to be to select some formula from anywhere but to sit down and derive the expression I need from my understanding of the situation. Then, in case I am not sure I have all the definitions at hand (because I made them) and can discuss with others on that basis. (Alternatively, if the problem appears too complex for me to handle it, I approach colleagues for help, but not without indicating the source of my information [which would include the definitions]).

So I cannot comment the formula above because I don't know what exactly the meaning of each symbol is meant to be. I can guess that "M" stands for some mass, V for some volume, with "z" and "N" I don't know what they are meant to represent.

Start with GaAs. You will easily find both its cubic lattice constant and its density in the literature. Go and see whether you understand how their values are related.

For Ga1-xMnxAs  you will probably have to make an assumption on how the Mn is being incorporated in the material. One possibility is to assume that all Mn atoms substitute Ga substitutionally. So, for the mass of the Ga sites you substitute mGa by (1-x) mGa+x mAs. If the lattice constant changes upon substitution, use it to re-evaluate the volume of the unit cell.

Does this help you finding the desired result?

Dear Sir,

I am sorry

In the above formula,

M= molar mass,

z= no. of atoms per unit cell or no. of formula units per unit cell?

V= volume of unit cell and

N= Avogadro no.

I am calculating volume by using the lattice parameter of doped sample.

Z is the number of formula units per unit cell. Example: For CuInTe2 Z=4 since there is 8 Te, 4 Cu and 4 In atoms is the chalcopyrite unit cell.

Dear Prof. Gallardo, thank you for the kind help.