DOI: 10.13012/b2idb-1409842_v3
title: Data for Observation of a Dynamic Magneto-chiral Instability in Photoexcited Tellurium

description: This repository provides the data and code used to reproduce key plots from the manuscript and to extend discussions that were only briefly covered therein. All MATLAB scripts were developed and tested in MATLAB R2024a. All Python scripts were developed and tested in Python 3.11.2.

* <b> NOTE:</b> New in this V3: 
1. 2 new MATLAB files (ChiralPointGroups.m and THz_current_estimation.m), ChiralPointGroups.pdf (a compiled version of ChiralPointGroups.m) and theoretical model code (theoretical_model.zip) are added. More information can be found in the readme. 
2. Updated and renamed "publication_data.zip" (in V2) to "data_and_analysis.zip" 
3. Change License from CC BY to "Other license". Licensing Terms: Data (all .mat files) is under CC BY and Code is released under MIT license. Therefore, V3 is bound to this new license. V2 is still under CC BY. 

<b>→ Data and analysis code (data_and_analysis.zip):</b>
The dataset is organized into five subfolders. Each subfolder corresponds to a unique combination of experimental conditions, including:
• Magnetic field orientation (B ∥ c or B ⟂ c)
• Scan parameter (magnetic field or temperature)
• Pump laser polarization (linear s, linear p, or circular)
• Detection polarization (linear s)
Each folder contains:
• The raw time-domain data files (.mat)
• Oscillator parameters extracted via linear prediction algorithm (.mat)
• MATLAB scripts (.m) that generate plots of the raw data, processed fits, and amplified modes. Each script should be run within its corresponding folder to ensure proper loading of the associated data files.

Folder summary:
1. B_parallel_c_linear_spump_sprobe_field: B ∥ c, s-polarized pump, s-polarized THz detection, magnetic field dependence
2. B_parallel_c_linear_spump_sprobe_temperature: B ∥ c, s-polarized pump, s-polarized THz detection, temperature dependence
3. B_perp_c_linear_spump_sprobe_field: B ⟂ c, s-polarized pump, s-polarized THz detection, magnetic field dependence
4. B_perp_c_linear_spump_sprobe_temperature: B ⟂ c, s-polarized pump, s-polarized THz detection, temperature dependence
5. B_parallel_c_LCPRCP_pump_sprobe_field: B ∥ c, circularly polarized pump (LCP & RCP), s-polarized THz detection, magnetic field dependence

<b>→Theoretical model code (theoretical_model.zip):</b>
The Python script depends on packages “numpy” and “matplotlib”. The script generates a plot of the dispersion relations of the theoretical model introduced in the Main Text. More precisely, it plots the real (red) and imaginary (blue) parts of the frequency (ω) as a function of wavenumber (k) as obtained by solving the characteristic equation, equation (6) of the Supplemental Information, with σ_E and σ_Μ given respectively by equations (3) and (2) of the Main Text. All branches of the dispersion relations are plotted simultaneously. All model parameters are adjustable.
The included Mathematica notebook (printout also provided in .pdf format) was used to obtain symbolic expressions for the coefficients of powers of ω appearing in the characteristic determinant. These coefficients were copied directly into the Python function detCoeffs().

<b>→ Standalone scripts (not in subfolders):</b>
• ChiralPointGroups.m
Outputs a table summarizing the 2D matrix representation of σ_Μ in the 11 enantiomorphic point groups. ChiralPointGroups.pdf is a compiled version of chiral point groups table, identical to the output of ChiralPointGroups.m.

• THz_current_estimation.m
Estimates the photoinduced THz current in tellurium under magnetic field. The script evaluates a phenomenological resonant contribution to the magnetoelectric coupling (with negligible dependence on NIR polarization), leading to excitation of s-polarized, B-antisymmetric mode S_odd at ~0.37 THz.

These standalone scripts provide additional physical discussion and calculation detail that are intentionally streamlined or omitted from the published manuscript and its supplementary materials for clarity and space.