[Wien] Magnetocrystalline anisotropy

[Xavier Rocquefelte]

Dear Colleagues

I recently obtained a surprising result concerning the calculation of 
the magnetocrystalline anisotropy energy (MAE) of SeCuO3.

This compound has a monoclinic symmetry (SG. P21/n) and is known to be 
antiferromagnetically ordered at low temperature.

Here I provide the results obtained for two magnetic orders, named FM 
and AFM1 (see attached document) :

https://filesender.renater.fr/?s=download&token=1da93a22-9592-3a7e-ba2e-1533fcae45d2

These calculations have been done using WIEN2k_17, GGA = PBE, RKMAX = 6, 
kmesh = 5 4 4 and in P1 symmetry. The results are the same using RKMAX = 7.

The AFM1 order is the more stable one, as expected.

However, as shown in the document the MAE of AFM1 order is not 
symmetric, which is not expected. In contrast the MAE for FM order is 
symmetric.

Based on the recent discussion "zigzag potential", it seems to me that 
the AFM1 MAE should be symmetric, because the magnetic moment is a 
pseudo-vector. Is it possible that the present problem is related to the 
fact that in the present implementation of the spin-orbit coupling we 
neglect the off-diagonal terms? Do you have any idea about the problem 
we are facing? Does someone observe such unusual MAE for other systems?

Best Regards

Xavier