CD-FISC: Field-Induced Superconductivity in Normal Materials

📄 Reference

L. Pan and M. Tanik, "Field-Induced Superconductivity in Normal Materials: A Communication Dynamics Framework" (2026).

Companion Paper (Paper I):
L. Pan and M. Tanik, "Communication Dynamics: An error-content Fourier-channel framework for atomic energy prediction, superconductor screening, and multi-domain materials design," Phys. Rev. X (companion paper) (2026).

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🎯 Overview

This repository implements the Communication Dynamics (CD) framework for predicting field-induced superconductivity in normal materials. The code extends the zero-field CD pairing susceptibility χ_CD(A,B) from Paper I with five distinct field-modification channels:

Five Field-Modification Mechanisms

Mode	Mechanism	Eq.	Key Physics
FZB	Zeeman pair-breaking	(3)	Magnetic field suppresses Cooper pairing
FJP	Jaccarino-Peter compensation	(4-5)	Exchange field compensates external field
FISO	Ising spin-orbit pinning	(6)	2D spin-orbit coupling protects pairs
FFM	FM-fluctuation enhancement	(7)	Ferromagnetic fluctuations boost pairing
FTOP	Topological proximity	(8)	Topological edge states enhance Tc

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🔬 Validated Against Experiments

The framework reproduces experimental observations for:

• UTe₂ (three superconducting phases at 0T, 10T, 73T)
• URhGe (re-entrant superconductivity with two-bump structure at 12T)
• CeRh₂As₂ (Pauli-limit violation: Hc2/HP = 3.5)
• λ-(BETS)₂FeCl₄ (Jaccarino-Peter compensation field Bcomp ≈ 50T)

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📊 Key Predictions

Top JP-Route Candidates (Table V)

Compound	Opt B (T)	Tc (K)	Mechanism
Pd-Mn	35-50	20-25	JP compensation
Pt-Ce	30-45	15-22	JP + heavy-fermion
Pd-Fe	40-50	18-23	JP compensation
Pt-U	25-35	12-18	JP + 5f-electron

Ising 2D Candidates (Table VII, B=50T)

Compound	Tc (K)	B_SO (T)	Mechanism
Pd-Mo	15.8	76	Ising SOC
Pt-W	14.2	88	Ising SOC
Y-Mo	12.5	71	Ising SOC

Noble-Metal Verdict (Section V)

❌ All 18 noble-metal/magnetic-ion combinations (Cu, Ag, Au × Mn, Fe, Co, Ni, Ce, U) have peak Tc < 1 mK → Field-induced SC is ruled out for noble metals.

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🚀 Usage

Quick Start

# Run full pipeline (validation + predictions + database)
python3 cd_fisc.py

# Validation anchors only
python3 cd_fisc.py --validate

# Noble-metal verdict only
python3 cd_fisc.py --noble

# Field-induced SC predictions only
python3 cd_fisc.py --predict

# Custom output directory
python3 cd_fisc.py --outdir my_results

Output Files

• cd_fisc_predictions.json – Full predictions database (JSON)
• cd_fisc_database.csv – Flat CSV for ML integration (86 candidates × 21 fields)

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📊 Visualization

Generate publication-quality plots with visualize.py:

# Install matplotlib (optional, for visualization only)
pip3 install matplotlib

# Generate all plots
python3 visualize.py --all

# Top 10 candidates bar chart
python3 visualize.py --top-n 10

# Field scan for a specific compound
python3 visualize.py --compound Pd-Mn

# Validation traces (UTe2, URhGe)
python3 visualize.py --validation

# Compare modes (JP/ISO/FM/ZB/TOP)
python3 visualize.py --mode-compare

Example Plots

• Top candidates: Horizontal bar chart of peak Tc values
• Field scans: Tc(B) curves for individual compounds
• Validation traces: URhGe re-entrant behavior, JP dome
• Mode comparison: Boxplots of Tc distributions by mechanism

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📦 Dependencies

Standard library only – no external packages required:

• math, json, csv, argparse, dataclasses

Python 3.8+ recommended.

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🧮 Theoretical Framework

Core Workflow

1. Zero-field susceptibility χ₀(A,B) from Paper I (polygon-DFT/Fourier-channel)
2. Field modification χ(B) = χ₀ × F(B) via active mode (ZB/JP/ISO/FM/TOP)
3. Electron-phonon coupling λ_CD = χ(B) × N(EF) × ξ(A,B)
4. Critical temperature Tc(B) via Allen-Dynes-McMillan equation (11)

Key Equations

• Eq. (1): Zero-field susceptibility χ_CD(A,B) (hydrogenic skeleton)
• Eq. (3): Zeeman factor F_ZB(B) = exp(-(B/B*)²)
• Eq. (4-5): JP factor F_JP(B) with compensation field Bcomp = J·μ·100T
• Eq. (9): λ_CD = χ·N(EF)·ξ (capped at 4.0)
• Eq. (11): Allen-Dynes-McMillan Tc = (ω/1.2)·exp[-1.04(1+λ)/(λ-μ*(1+0.62λ))]

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📁 Repository Structure

CD-FISC/
├── cd_fisc.py              # Main production code
├── visualize.py            # Visualization toolkit (requires matplotlib)
├── README.md               # This file
├── LICENSE                 # MIT License
├── CITATION.cff            # Citation metadata
├── examples/               # Pre-generated outputs
│   ├── cd_fisc_predictions.json
│   └── cd_fisc_database.csv
└── figures/                # Generated plots (git-ignored)

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🔍 Design Note on χ₀

The present paper takes the zero-field χ_CD(A,B) as an input from Paper I (stored in CHI0_DB) and extends it with field modes. The schematic closed-form chi_cd_eq1() is provided for transparency, but production values come from the calibrated Paper-I polygon-DFT database. This is faithful to the paper's logic: the contribution of the present work is the field extension, not a re-derivation of χ₀.

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📈 Example: UTe₂ Validation

# UTe₂ SC1 (zero field)
python3 cd_fisc.py --validate

Output:

UTe2  B=0:    chi=0.254, xi=16, lambda=0.297, omega_log=173.7 K, Tc=1.80 K
                                                    (exp: 1.6 K) ✓

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🧪 Full Database

The code scans 86 candidate compounds across 21 field points (0–100T at 5T resolution):

• 12 normal metals × 6 magnetic ions (JP/FM/Zeeman channels)
• 12 normal metals × 4 heavy partners (Ising 2D channel at 50T)

Total: 1,512 JP records + 48 Ising records = 1,560 Tc(B) predictions

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🤝 Contributing

Contributions are welcome! Please open an issue or submit a pull request.

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📜 License

MIT License – see LICENSE for details.

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📧 Contact

Lurong Pan
GitHub: @lurongpan47

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🌟 Citation

If you use this code in your research, please cite:

@article{pan2026cdfisc,
  title={Field-Induced Superconductivity in Normal Materials: A Communication Dynamics Framework},
  author={Pan, L. and Tanik, M.},
  journal={arXiv preprint arXiv:XXXX.XXXXX},
  year={2026}
}

@article{pan2026cd,
  title={Communication Dynamics: An error-content Fourier-channel framework for atomic energy prediction, superconductor screening, and multi-domain materials design},
  author={Pan, L. and Tanik, M.},
  journal={Physical Review X},
  year={2026}
}

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⚡ Happy field-induced superconductivity hunting!