McPhase

Official Resources

• Homepage: https://www2.cpfs.mpg.de/~rotter/homepage_mcphase/
• Documentation: https://www2.cpfs.mpg.de/~rotter/homepage_mcphase/manual/manual.html
• Source Repository: Distributed via website (GPL)
• License: GNU General Public License v3.0

Overview

McPhase is a software package for calculating magnetic phase diagrams and thermodynamic properties of magnetic materials. It uses a mean-field approximation combined with Monte Carlo simulations to treat localized magnetic moments in crystal fields. It is particularly specialized for rare-earth magnetism, handling crystal electric field (CEF) effects, exchange interactions, and magneto-elastic coupling.

Scientific domain: Magnetic phase diagrams, rare-earth magnetism, crystal fields
Target user community: Solid-state physicists, neutron scattering researchers

Theoretical Methods

• Mean Field Theory (for magnetic ordering)
• Crystal Electric Field (CEF) theory (Stevens operators)
• Monte Carlo simulation (for phase diagrams)
• Random Phase Approximation (RPA) for excitations
• Dipole approximation for magnetic moments
• Multipole interactions

Capabilities (CRITICAL)

• Calculation of magnetic phase diagrams (H-T, P-T)
• Simulation of specific heat, magnetization, susceptibility
• Calculation of magnetic excitations (spin waves, crystal field levels)
• Neutron scattering cross-sections (elastic and inelastic)
• Handling of complex magnetic structures (commensurate/incommensurate)
• Magnetostriction and magneto-elastic effects

Sources: McPhase website, J. Magn. Magn. Mater. 272, E481 (2004)

Inputs & Outputs

• Input formats: .mcphase (control), .sipf (interaction parameters), .j1 (exchange constants)
• Output data types: .out (thermodynamics), .calc (calculated properties), .jpg/png (phase diagrams)

Interfaces & Ecosystem

• Simplot: Built-in plotting tool
• Display: Visualization of magnetic structures
• Mcdisp: Module for dispersion relations
• Fit: Fitting module for experimental data

Workflow and Usage

1. Define crystal structure and magnetic ions.
2. Parameterize Crystal Field (point charge or DFT fitted).
3. Define exchange interactions.
4. Run mcphas to calculate free energy and stabilize magnetic structure.
5. Run mcdisp for excitations.

Performance Characteristics

• Mean field calculations are fast
• Monte Carlo steps can be time-consuming for large phase diagrams
• Efficient for localized moment systems

Application Areas

• Rare-earth intermetallics
• Multiferroics
• Frustrated magnets
• Interpretation of neutron scattering data
• Magnetocaloric effect

Community and Support

• Developed by Martin Rotter (Dresden/McPhase group)
• Academic user base
• Comprehensive manual and examples

Verification & Sources

Primary sources:

1. Homepage: https://www2.cpfs.mpg.de/~rotter/homepage_mcphase/
2. Publication: M. Rotter et al., J. Magn. Magn. Mater. 272, E481 (2004)

Confidence: VERIFIED

Verification status: ✅ VERIFIED

• Website: ACTIVE
• Documentation: AVAILABLE
• Source: OPEN (GPL)
• Development: ACTIVE (Rotter)
• Applications: Magnetic phase diagrams, CEF, rare-earths