The Bohr magnetron per upaired spin (SI): mu_b=e*(h/2*pi)/(2*m_e). mu_b = 9.274 009 15 × 10−21 erg/G (EMU) = 9.27400968(20)×10−24 J/T (SI)

but this formula goes for theoretical calculations using effective mass . Is there any formula that uses VSM results for the calculations?

M_e is just the electron mass

Dear Ralf,

Can i get the reference for this formula?

You need to know the molecular weight and the amount of mass of your compound used for the magnetization measurement. Then, the conversion factor is that I explain in the attachment.

Thank you Mr. Pedro Gorria for your kind help. Further regarding this formula the calculations i am intending on doing are on thin films and i have the saturation magnetization values in "emu". In case of powder materials to convert it to emu/g we divide it by the mass. But how to convert emu to emu/g for thin films?

Aseya, when you make a measurement in a magnetometer you always obtain "emu", but you MUST know the mass of the sample that contributes to the magnetic signal, otherwise you CANNOT say anything about the magnetization or the magnetic moment of your sample. It is evident that two different samples with very different magnetization values could give similar magnetic signals in "emu", it depends on the amount of mass used for the measurement. I know that it is not an easy task to accurately estimate the mass of a thin film, but it is the only way to determine the magnetization of the sample from a measurement performed using a magnetometer such as a VSM or SQUID.

I attached file , in that i clearly explained steps how the final conversion come. Reference for that is B.D. Cullity introduction to magnetic materials.

Dear Pedro Gorria what we do in case of thin films(1nm thickness).How we measure the magnetic moment per atom???

Dear Sajid,

If you measure the magnetization in emu, you need to know the mass of your sample in order to estimate either the magnetization in emu/g (or A m^2/kg) or the magnetic moment in Böhr magnetons.

Best,

Pedro

Dear Alejandro,

You don't need the value of the applied magnetic field for the calculations. However, the value of H has to be large enough to reach the saturation regime for the magnetization. Anyway, to get the value of Ms as accurate as possible a law of approach to saturation (see Cullity or our recent paper in JMMM) must be used for the fit of the M(H) curves. The value of Ms is not that corresponding to the maximum applied field.

Best,

Pedro

I have thin film of 60 nm thickness. I want to calculate UB/atom...how to calculate ???

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Let nB be the number of Bohr magnetons per atom, which we will calculate. By the definition of magnetization

nB  = Ms/µB.N  

Where Ms=  saturation magnetization.  µB = Bohr magnetons constant which equal to 9.27× 10^-24 amp/m2

where N is the number of atoms per cubic meter. This found from the number of atoms per unit cell.

N=2/a^3 for bcc. N= 4/a^3 for fcc  where a= lattice parameter

Thin films (LxWxH) of the sample in cm give you the volum in cm3.

If you would like to convert from thin films (cm3) to powder (gram) or from powder (gram) to thin films (cm3) you have to divided or mulitply by the Density (gram/cm3) of your material.

Regards,

you will find the answer in the following paper

Article Magneto-optical and microstructural properties of spinel cub...

@ Prasenjit Singha "µB = Bohr magnetons constant which equal to 9.27× 10^-24 amp/m2", the unit of uB in SI should be J/T=Am^2.

Ms can be emu/g; uB/g; uB/f.u.;

Ms from uB/f.u. to A/m: (n, multiples from f.u. to unit cell) * (Am^2, change to this unit)/(m^3, volume for a unit cell) (note: times a value N so as to correspond to a unit cell)

Dear Aseya Akbar

Please read the attached file.