Magnetisation and magnetization (some doubts about )
Posted: Fri Aug 24, 2012 6:40 pm
Hi, following the spin tutotorial (part 1, bcc Fe), I get confused of some points and I wonder if anyone can help clear my mind about this:
1) "Spinat" input variable
It is declared as "Gives the initial electronic spin-magnetisation for each atom, in unit of h-bar/2." wich seems confusing to me. Magnetic moments of atoms are expressed in Ampere (times) metre square (Joule/Tesla in SI or emu in CGS) wich in the case of Iron it is known as 2,2 bohr magnetons. It is indicated in the input file of Fe as "spinat 0. 0. 4." wich seems to be the sum of the value of spins (has the units of spin eigenvalues) of the 2 s electrons of iron (I do not understand as "the spin-magnetization). Is that like I said?
2) Outputs Magnetization and Magnetisation:
What is generally reported in scientific literature as "Magnetization" with letter M (independently of if is saturation or remanent or other) is the magnetic moment per volumen (also know as magnetization per volume). Wich is units of Ampere/metre (or emu/cm^-3). Also in literature is reported the magnetization per unit mass (indicated with greek letter sigma) wich has units of Ampere x metre square / kilograma (or in CGS as emu/g). In "Introduction to Magnetic Materials" of Cullity-Graham book, it is reported at 0 K that iron has sigma_0 = 221,9 emu/g. While if you look at the ouput of running tutotorial spin 1 (/abinit6.x.x/test/tutorial/tspin_1.in) there two "magnetizations":
2.A First it is reported the Magnetization as "(spin up - spin down) [el/Bohr^3]" with its minimums and maximums.
I do not understand the usefullness of this reported values, even more I do not understand why the spins are not all "paralel" at 0 K.
2.B There is a second report as Magnetisation (with s instead of z), wich is reported in " Magnetisation (Bohr magneton)= 1.96743487E+00". Wich seems to be the magnetic moment per atom (sometimes reported as (greek letter mu)_H and should be 2,219 (page 531 of Cullity-Graham) instead of 1,967 Bohr magnetons. Here if this value is what I guess I do not understand why is not called like it should (meaning "Magnetic moment per atom"), and why the non-deprecible difference with reported values cited. Even more, during that ABINIT can compute volumen and density, I do not understand why ABINIT does not report Magnetization per volumen or per mass.
If anyone can solve my doubts I would be very gratefull.
1) "Spinat" input variable
It is declared as "Gives the initial electronic spin-magnetisation for each atom, in unit of h-bar/2." wich seems confusing to me. Magnetic moments of atoms are expressed in Ampere (times) metre square (Joule/Tesla in SI or emu in CGS) wich in the case of Iron it is known as 2,2 bohr magnetons. It is indicated in the input file of Fe as "spinat 0. 0. 4." wich seems to be the sum of the value of spins (has the units of spin eigenvalues) of the 2 s electrons of iron (I do not understand as "the spin-magnetization). Is that like I said?
2) Outputs Magnetization and Magnetisation:
What is generally reported in scientific literature as "Magnetization" with letter M (independently of if is saturation or remanent or other) is the magnetic moment per volumen (also know as magnetization per volume). Wich is units of Ampere/metre (or emu/cm^-3). Also in literature is reported the magnetization per unit mass (indicated with greek letter sigma) wich has units of Ampere x metre square / kilograma (or in CGS as emu/g). In "Introduction to Magnetic Materials" of Cullity-Graham book, it is reported at 0 K that iron has sigma_0 = 221,9 emu/g. While if you look at the ouput of running tutotorial spin 1 (/abinit6.x.x/test/tutorial/tspin_1.in) there two "magnetizations":
2.A First it is reported the Magnetization as "(spin up - spin down) [el/Bohr^3]" with its minimums and maximums.
I do not understand the usefullness of this reported values, even more I do not understand why the spins are not all "paralel" at 0 K.
2.B There is a second report as Magnetisation (with s instead of z), wich is reported in " Magnetisation (Bohr magneton)= 1.96743487E+00". Wich seems to be the magnetic moment per atom (sometimes reported as (greek letter mu)_H and should be 2,219 (page 531 of Cullity-Graham) instead of 1,967 Bohr magnetons. Here if this value is what I guess I do not understand why is not called like it should (meaning "Magnetic moment per atom"), and why the non-deprecible difference with reported values cited. Even more, during that ABINIT can compute volumen and density, I do not understand why ABINIT does not report Magnetization per volumen or per mass.
If anyone can solve my doubts I would be very gratefull.