Spin polarization induced by magnetic field

[Andrew Shyichuk]

Dear Users,

It is known that magnetic fields are used in Elk in order to constrain or initiate magnetization.

Is it possible to obtain the same effect in an actual material?
For instance, can we force d electons from a low-spin ground state into a high-spin excited state by a static magnetic field? How strong the field should be?

The only similar thing I found is Pauli paramagnetism, which is manifested as a shift between spin-up and spin-down bands under external magnetic fields. Are there other related effects?

Thanks.
Andrew

[J. K. Dewhurst]

Dear Andrew,

All materials have a diamagnetic response, including frogs.

If you are close to a magnetic phase transition, the response of the moment to a magnetic field can be large. For common ferromagnets (Fe, Co, Ni) the magnitude of the moment will not be much affected by small fields (a few tesla). However, the direction can be changed by small fields, as seen for example in hysteresis curves. In the absence of spin-orbit coupling, states corresponding to different directions of the moment are degenerate.

In Elk a magnetic field of magnitude 1 in atomic units corresponds to 1715 Tesla, which indicates that very large fields would be needed to affect the basic chemistry of a material.

Regards,
Kay.

[Andrew Shyichuk]

Dear Kay,

So, the effect is physical in principle, although we are talking crazy high fields? I am not going to make publishable conclusions based on that, at least not without an experiment. The question is rather: "There is this thing I can do with magnetic field in Elk, is it a legit reason to try an experiment?"

I also noticed, that sometimes I cannot induce a stable magnetic moment with bfiledc = 1 or even more, but fsmtype = 1 results in a desired moment with a FSM global effective field of, say, 0.05 or much less (importantly - in the range of achievable fields). Why is it so?

Best regards.
Andrew

[Jerry Li]

Hello Andrew,

Have you got any correct hysteresis curve in your Elk computation? I want to calculate hysteresis loop for the ferromagnetism of oxygen vacancy in some compounds, but don't have any clue. I appreciate it if you succeed and can share your elk.in file.

Best regards
Jerry