Error with multiple RKKY energies

[brevisf]

Hello!
I'm trying to simulate a multilayer system, for example with three magnetic layers and two spacers. I want to couple Layer1 with Layer2 and Layer 2 with Layer3 through RKKY energy term. Also I need to implement two Uniaxial anisotropies, which gave me no issues, but when I try to add two RKKY interactions, the code fails: "Key Oxs_LinearScalarField:rkkyfield already in use". So, it is not possible to add more RKKY interactions?

Thanks !

Felipe Brevis

system = mm.System(name="rkky")
system.energy = (
    mm.Exchange(A=1e-12) + mm.RKKY(sigma=-1e-4, sigma2=0, subregions=['layer1', 'layer2bottom'], name="rkky_12")
    + mm.RKKY(sigma=-1e-4,sigma2=0,subregions=['layer2top', 'layer3'], name="rkky_23")
    + mm.UniaxialAnisotropy(K=0.5e6, u=(0, 0, 1), name='OOP_anisotropy') + mm.UniaxialAnisotropy(K=0.5e6, u=(1, 0, 0), name='IP_anisotropy')
)

[lang-m]

Hi @brevisf, to include the same energy term multiple times you need to give each instance a unique name as explained in https://ubermag.github.io/examples/notebooks/multiple-terms.html

[brevisf]

Hi ! Thank you very much for your answer but I actually did that, as is shown in the code lines, for Uniaxial anisotropies and RKKY interactions. For Uniaxial anisotropies it works, but not for RKKY.

Thanks !

[lang-m]

Thanks for pointing that out, I overlooked the name arguments. I can confirm that the RKKY implementation specifically does not allow more that one RKKY term.

The following patch should presumably fix the issue, but I don't have time right now to properly test this. You could try to adapt you installation. If you do I would advise you to also read the relevant section in the OOMMF documentation, https://math.nist.gov/oommf/doc/userguide21a1/userguide/Energies.html#PTTS, to be aware of any side-effects this may have.

diff --git a/oommfc/scripts/energy.py b/oommfc/scripts/energy.py
index 25c1cc7..2ccb622 100644
--- a/oommfc/scripts/energy.py
+++ b/oommfc/scripts/energy.py
@@ -404,7 +404,7 @@ def rkky_script(term, system):
     mif = ""
 
     mif += "# Scalar field for RKKY surfaces\n"
-    mif += "Specify Oxs_LinearScalarField:rkkyfield {\n"
+    mif += f"Specify Oxs_LinearScalarField:{term.name}field {\n"
     vectorval = df.util.assemble_index(
         0, 3, {system.m.mesh.region._dim2index(direction): 1}
     )
@@ -422,7 +422,7 @@ def rkky_script(term, system):
     mif += "  surface1 {\n"
     mif += "    atlas :main_atlas\n"
     mif += f"    region {first_name}\n"
-    mif += "    scalarfield :rkkyfield\n"
+    mif += f"    scalarfield :{term.name}field\n"
     mif += f"    scalarvalue {first.pmax[system.m.mesh.region._dim2index(direction)]}\n"
     mif += "    scalarside -\n"
     mif += "  }\n"
@@ -430,7 +430,7 @@ def rkky_script(term, system):
     mif += "  surface2 {\n"
     mif += "    atlas :main_atlas\n"
     mif += f"    region {second_name}\n"
-    mif += "    scalarfield :rkkyfield\n"
+    mif += f"    scalarfield :{term.name}field\n"
     mif += (
         f"    scalarvalue {second.pmin[system.m.mesh.region._dim2index(direction)]}\n"
     )

[brevisf]

Many thanks!! It looks that it worked !! [image: image.png] El lun, 23 jun 2025 a las 3:25, Martin Lang ***@***.***>) escribió:

…

*lang-m* left a comment (ubermag/help#323) <#323 (comment)> Thanks for pointing that out, I overlooked the name arguments. I can confirm that the RKKY implementation specifically does not allow more that one RKKY term. The following patch should presumably fix the issue, but I don't have time right now to properly test this. You could try to adapt you installation. diff --git a/oommfc/scripts/energy.py b/oommfc/scripts/energy.py index 25c1cc7..2ccb622 100644--- a/oommfc/scripts/energy.py+++ b/oommfc/scripts/energy.py@@ -404,7 +404,7 @@ def rkky_script(term, system): mif = "" mif += "# Scalar field for RKKY surfaces\n"- mif += "Specify Oxs_LinearScalarField:rkkyfield {\n"+ mif += f"Specify Oxs_LinearScalarField:{term.name}field {\n" vectorval = df.util.assemble_index( 0, 3, {system.m.mesh.region._dim2index(direction): 1} )@@ -422,7 +422,7 @@ def rkky_script(term, system): mif += " surface1 {\n" mif += " atlas :main_atlas\n" mif += f" region {first_name}\n"- mif += " scalarfield :rkkyfield\n"+ mif += f" scalarfield :{term.name}field\n" mif += f" scalarvalue {first.pmax[system.m.mesh.region._dim2index(direction)]}\n" mif += " scalarside -\n" mif += " }\n"@@ -430,7 +430,7 @@ def rkky_script(term, system): mif += " surface2 {\n" mif += " atlas :main_atlas\n" mif += f" region {second_name}\n"- mif += " scalarfield :rkkyfield\n"+ mif += f" scalarfield :{term.name}field\n" mif += ( f" scalarvalue {second.pmin[system.m.mesh.region._dim2index(direction)]}\n" ) — Reply to this email directly, view it on GitHub <#323 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AO4WZ3JLIANMXZQSRERRT6D3E6TVBAVCNFSM6AAAAAB7WZFHXCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDSOJVGI2DONBVG4> . You are receiving this because you were mentioned.Message ID: ***@***.***>