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SPXAS

 

For antiferromagnets, the XMCD should be zero. SPXAS is a different technique where you measure spin-up and spin-down signal by measuring intensity of two spin-split Kbeta lines. This corresponds to measuring spin-order relative to the spin on the absorber ( not relative to the external magnetic field as in XMCD). As an example, let us look at the Mn K edge of antiferromagnetic MnF2. Our calculations agree well with experiment in EXAFS region.

Here is the input file for MnF2.

 TITLE   MnF2 (rutile) cassiterite (Wykoff)

 HOLE 1   1.0     1=k edge, s0^2=1.0
 SPIN  -2

 CONTROL   1      1     1     1     1     1
 PRINT     0      0     0     2     0     4
 EXCHANGE  0  0.0  0.0
 CORRECTIONS  0.0   0.0

 RPATH  10.0
 XANES

 PCRITERIA       0.8     40.0
 *CRITERIA     curved   plane
 CRITERIA       0.0     0.0
 *DEBYE        temp     debye-temp
  DEBYE        300       350
 NLEG         4

 POTENTIALS
 *   ipot   z  label
       0   25   Mnup
       1    9   F
       2   25   Mnup
       3   25   Mndown

 ATOMS
   0.0000     0.0000     0.0000    0   Mnup             0.0000
   1.4864     1.4864     0.0000    1   F                2.1021
  -1.4864    -1.4864     0.0000    1   F                2.1021
   0.9503    -0.9503     1.6550    1   F                2.1319
   0.9503    -0.9503    -1.6550    1   F                2.1319
  -0.9503     0.9503     1.6550    1   F                2.1319
  -0.9503     0.9503    -1.6550    1   F                2.1319
   0.0000     0.0000    -3.3099    3   Mndown           3.3099
   0.0000     0.0000     3.3099    3   Mndown           3.3099
  -3.3870     1.4864     0.0000    1   F                3.6988
   3.3870    -1.4864     0.0000    1   F                3.6988
   1.4864    -3.3870     0.0000    1   F                3.6988
  -1.4864     3.3870     0.0000    1   F                3.6988
   2.4367     2.4367    -1.6550    2   Mnup             3.8228
  -2.4367    -2.4367    -1.6550    2   Mnup             3.8228
   2.4367    -2.4367    -1.6550    3   Mndown           3.8228
  -2.4367    -2.4367     1.6550    3   Mndown           3.8228
  -2.4367     2.4367    -1.6550    3   Mndown           3.8228
   2.4367     2.4367     1.6550    3   Mndown           3.8228
   2.4367    -2.4367     1.6550    2   Mnup             3.8228
  -2.4367     2.4367     1.6550    2   Mnup             3.8228
 ...
END




John J. Rehr
Thu Jul 1 14:31:17 PDT 1999