v1.2.2

.github/workflows/build-wheels.yml

@@ -19,7 +19,7 @@ jobs:
       matrix:
         os:
           - {name: "ubuntu", version: "22.04"}
-          - {name: "windows", version: "latest"}
+          - {name: "windows", version: "2022"}
         cuda: ["12.4.1"]
         python: ["3.11", "3.12", "3.13", "3.14"]
 
@@ -129,7 +129,7 @@ jobs:
 
     steps:
       - name: Download all artifacts
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v7
         with:
           path: artifacts
 
@@ -158,6 +158,6 @@ jobs:
         with:
           tag_name: ${{ github.event.release.tag_name || github.event.inputs.tag }}
           files: dist-gh-release/*
-          overwrite: true
+          overwrite_files: true
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/deploy-docs.yml

@@ -14,7 +14,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Deploy docs/_build/html to GitHub Pages
         uses: peaceiris/actions-gh-pages@v4

docs/_static/custom.css

@@ -21,3 +21,7 @@ html[data-theme="dark"] .navbar-brand img {
    display: block;
    width: 100%;
 }
+
+.bd-sidebar-primary .navbar-icon-links {
+  justify-content: space-evenly !important;
+}

docs/api.rst

@@ -28,6 +28,7 @@ API
    PoissonSystem
    DmiTensor
    BoundaryTraction
+   Window
 
 .. toctree::
    :maxdepth: 1

docs/examples.rst

@@ -13,3 +13,4 @@ Here we show some example Python scripts to run mumax⁺ simulations.
    examples/DW_SAW
    examples/voronoi
    examples/Bloch_wall_altermagnet
+   examples/moving_window

docs/examples/moving_window.rst

@@ -0,0 +1,22 @@
+:nosearch:
+
+Moving simulation window
+========================
+
+In this example we move a domain wall in a ferromagnet using a Zhang-Li STT. We let the simulation
+window move together with the wall, keeping the domain wall centered in the simulation space.
+Using this, we can virtually simulate an infinitely long magnetic nanowire using a limited number
+of simulation cells.
+
+Note:
+The moving window functionality only works properly if
+- The magnet parameters are uniform
+- The magnet has no geometry
+- The magnet has no regions
+
+.. literalinclude:: ../../examples/moving_window.py
+  :language: python
+  :lines: 13-
+
+.. video:: ../images/moving_window.mp4
+   :align: center

examples/Bloch_wall_altermagnet.py

@@ -21,13 +21,10 @@
 A12 = A0/2
 
 length = 256e-9
-width = 64e-9
 
 # ----------- Create altermagnet -----------
 
 Nx = int(length / cs)
-Ny = int(width / cs)
-
 world  = World((cs, cs, cs))
 grid   = Grid((Nx, 1, 1))
 magnet = Altermagnet(world, grid)

examples/moving_window.py

@@ -0,0 +1,146 @@
+"""
+In this example we move a domain wall in a ferromagnet using a Zhang-Li STT. We let the simulation
+window move together with the wall, keeping the domain wall centered in the simulation space.
+Using this, we can virtually simulate an infinitely long magnetic nanowire using a limited number
+of simulation cells.
+
+Note:
+The moving window functionality only works properly if
+- The magnet parameters are uniform
+- The magnet has no geometry
+- The magnet has no regions
+"""
+from mumaxplus import World, Grid, Ferromagnet
+from mumaxplus.util import twodomain, plot_field
+
+import matplotlib.pyplot as plt
+from matplotlib.animation import FuncAnimation, FFMpegWriter
+import numpy as np
+
+# ----------- Material and simulation parameters -----------
+cs = 1e-9
+length = 256e-9
+width = 64e-9
+thickness = 1e-9
+
+Ms = 600e3
+aex = 10e-12
+alpha = 0.02
+ku = 6e5
+anisU = (1, 0, 0)
+
+# ----------- Create magnet -----------
+world = World((cs, cs, cs))
+grid = Grid((int(length / cs), int(width / cs), int(thickness / cs)))
+
+magnet = Ferromagnet(world, grid)
+
+magnet.msat  = Ms
+magnet.aex   = aex
+magnet.alpha = alpha
+magnet.ku1   = ku
+magnet.anisU = anisU
+
+magnet.enable_demag = False
+magnet.enable_openbc = True
+
+
+# ----------- Create two domain state -----------
+magnet.magnetization = twodomain((1, 0, 0), (0, 1, 0), (-1, 0, 0), magnet.center[0], 5e-9)
+magnet.minimize()
+
+# ----------- Add current and simulate -----------
+magnet.jcur = (-1e12, 0, 0)
+magnet.xi   = 0.2
+magnet.pol = 1
+
+# Center the simulation window, keeping component 0 (x) close to zero.
+# We expect motion along the x axis.
+world.center_domain_wall(comp=0, axis=0)
+
+tmax = 0.5e-9
+timepoints = np.linspace(0, tmax, 100)
+
+def DW_pos(field):
+    mx = field[0, 0, int(width / cs/2), :]
+    sign = np.sign(mx)
+    # find cell where magnetization component crosses zero
+    i = np.where(np.diff(sign) != 0)[0][0]
+    # linearly interpolate
+    m1, m2 = mx[i], mx[i + 1]
+    return (i - m1 / (m2 - m1)) * cs
+
+outputquantities = {"mag": magnet.magnetization,
+                    "window position": lambda: world.window.position[0],
+                    "wall position": lambda: world.window.position[0] + DW_pos(magnet.magnetization())}
+
+output = world.timesolver.solve(timepoints, outputquantities, tqdm=True)
+
+p0 = output["wall position"][0]
+
+# ----------- Create movie -----------
+print("Creating animation...")
+fig, axes = plt.subplots(2, 1, figsize=(10, 7))
+
+# Time trace subplot
+ax_trace = axes[0]
+lines = {}
+keys = ["window position", "wall position"]
+for key in keys:
+    lines[key], = ax_trace.plot([], [], '-', label=key)
+
+ax_trace.set_xlim(0, tmax * 1e9)
+ax_trace.set_ylim(min(0, min(output["window position"]) * 1e9),
+                  max(0, max(output["wall position"] - p0) * 1e9))
+ax_trace.set_xlabel("Time $t$ (ns)")
+ax_trace.set_ylabel("position (nm)")
+ax_trace.legend()
+ax_trace.grid()
+
+# Magnetization image subplot
+ax_image = axes[1]
+plot_field(output["mag"][0], ax=ax_image, arrow_size=8)
+
+ax_image.set_xlim(0, int(length/cs))
+ticks = ax_image.get_xticks()
+
+ax_image.set_title("$t$ = 0.000 ns")
+ax_image.set_xlabel("$x$ (nm)")
+ax_image.set_ylabel("$y$ (nm)")
+
+fig.tight_layout()
+
+# --- Animation Function ---
+def update(frame):
+    # Update image
+    ax_image.clear()
+    plot_field(output["mag"][frame], ax=ax_image, arrow_size=8)
+    ax_image.set_xlabel("$x$ (nm)")
+    ax_image.set_ylabel("$y$ (nm)")
+
+    # update x-ticks
+    shift = output["window position"][frame] * 1e9
+    tick_positions = (ticks - shift)
+    mask = (0 <= tick_positions) & (tick_positions <= int(length/cs))
+
+    ax_image.set_xticks(tick_positions[mask])
+    ax_image.set_xticklabels([f"{t:.0f}" for t in ticks[mask]])
+    ax_image.set_title(f"$t$ = {output['time'][frame] * 1e9:.3f} ns")
+
+    # Update time trace
+    lines["window position"].set_data(np.array(output["time"][:frame+1]) * 1e9,
+                                      np.array(output["window position"][:frame+1]) * 1e9)
+    lines["wall position"].set_data(np.array(output["time"][:frame+1]) * 1e9,
+                                    np.array(output["wall position"][:frame+1] - p0) * 1e9)
+
+    return [ax_image] + list(lines.values())
+
+# Animation parameters
+fps = 15
+anim = FuncAnimation(fig, update, frames=len(output["time"]),
+                     interval=1000 / fps, repeat_delay=5000 / fps)
+
+# --- Save the animation ---
+save_filename = "moving_window.mp4"
+writer = FFMpegWriter(fps=fps)
+anim.save(save_filename, writer=writer)

examples/standardproblem2.py

@@ -30,7 +30,7 @@ def get_next_power_of_2(x):
         y *= 2
     return y
 
-def get_gridsize(L, d, t, l_ex=l_ex):
+def get_gridsize(L, d, t):
     """Cell length should at least be < l_ex/2. The number of cells is best
     a power of 2 for FFT. This results in cell sizes between 0.25*l_ex and
     0.5*l_ex."""
@@ -42,7 +42,7 @@ def get_gridsize(L, d, t, l_ex=l_ex):
     L = L_p_d * d  # dimensionless length L = length/l_ex
     t = t_p_d * d  # dimensionless thickness t = thickness/l_ex
 
-    nx, ny, nz = get_gridsize(L, d, t, l_ex=l_ex)
+    nx, ny, nz = get_gridsize(L, d, t)
     world = World(cellsize=(L*l_ex/nx, d*l_ex/ny, t*l_ex/nz))
     magnet = Ferromagnet(world, Grid((nx, ny, nz)))
     magnet.msat = msat

mumaxplus/__init__.py

@@ -55,6 +55,7 @@
 from .traction import BoundaryTraction
 from .variable import Variable
 from .world import World
+from .window import Window
 from . import util
 
 FP_PRECISION = {1: "SINGLE", 2: "DOUBLE"}.get(_cpp.FP_PRECISION, "UNKNOWN") # Use _cpp value, as that is certainly the correct one
@@ -77,6 +78,7 @@
     "TimeSolver",
     "Variable",
     "World",
+    "Window",
     "PoissonSystem",
     "util",
     "FP_PRECISION"

mumaxplus/ferromagnet.py

@@ -653,7 +653,7 @@ def B1(self) -> Parameter:
 
         See Also
         --------
-        B2
+        B2, B_chiral
         """
         return Parameter(self._impl.B1)
 
@@ -678,7 +678,7 @@ def B2(self) -> Parameter:
 
         See Also
         --------
-        B1
+        B1, B_chiral
         """
         return Parameter(self._impl.B2)
 
@@ -697,6 +697,36 @@ def B2(self, value):
                           + " is set to a positive value, instead of negative (or zero)."
                           + " Make sure this is intentional!", UserWarning)
 
+    @property
+    def B_chiral(self) -> Parameter:
+        r"""Chiral magnetoelastic coupling constant (J/m³).
+
+        Notes
+        -----
+        Materials of the cubic point group 23 (or B20 compounds) can have a
+        chiral magnetoelastic coupling, with the following energy density.
+
+        .. math:: \mathcal{E} = B_\text{chiral} \sum_{i, j, k} \epsilon_{ijk} \varepsilon_{ii} m_j^2
+
+        Here :math:`\epsilon_{ijk}` is the Levi-Civita symbol and
+        :math:`\varepsilon_{ii}` denotes the normal strain components.
+        This energy density comes from equations (8.12) and (8.16) in Ref. [1], where
+        B_chiral corresponds to :math:`\lambda_{12}`. Magnetoelastic coupling constants
+        B1 and B2 correspond to :math:`\lambda_{11}` and :math:`2 \lambda_{44}` respectively.
+        These lambdas are not the usual magnetostrictive coefficients.
+
+        .. [1] L\ . Franke, “Elastic Coupling at Quantum Phase Transitions and in Chiral Magnets,” Das Karlsruher Institut für Technologie, Karlsruhe, 2025. doi: 10.5445/IR/1000184834.
+
+        See Also
+        --------
+        B1, B2
+        """
+        return Parameter(self._impl.B_chiral)
+
+    @B_chiral.setter
+    def B_chiral(self, value):
+        self.B_chiral.set(value)
+
     # ----- POISSON SYSTEM ----------------------
 
     @property
@@ -1128,7 +1158,7 @@ def magnetoelastic_field(self) -> FieldQuantity:
 
         See Also
         --------
-        B1, B2
+        B1, B2, B_chiral
         Magnet.strain_tensor, Magnet.rigid_norm_strain, Magnet.rigid_shear_strain
         magnetoelastic_force
         """
@@ -1160,7 +1190,7 @@ def magnetoelastic_force(self) -> FieldQuantity:
 
         See Also
         --------
-        B1, B2
+        B1, B2, B_chiral
         Magnet.effective_body_force, magnetoelastic_field
         """
         return FieldQuantity(_cpp.magnetoelastic_force(self._impl))

mumaxplus/util/__init__.py

@@ -27,7 +27,7 @@
     "show_magnet_geometry",
     "show_field_3D",
     "show_regions",
-    # voronoi
+    # misc
     "VoronoiTessellator",
     "MFM"
 ]

mumaxplus/util/voronoi.py

@@ -6,6 +6,7 @@
 from .. import _cpp
 from mumaxplus.world import World
 from mumaxplus.grid import Grid
+
 class VoronoiTessellator: