1. ABOUT THE DATASET -------------------- Title: Creator(s): [Craig S. Knox, Matthew T. Vaughan, Andrew D. Burnett, Mannan Ali, Satoshi Sasaki, Edmund H. Linfield, Alexander Giles Davies and Joshua R. Freeman] Organisation(s): [University of Leeds] Publication Year: 2022 Description: [This is the dataset associated with the materials study performed on the IR active E1u phonon within the Bi2(Te(1-x)Sex)3 alloy system. It contains THz and DC conductivity data that show the change in phonon dynamics over a wide range of temperatures and stoichiometries. It also contains data and information about DFT calculations done in support of this work.] Cite as: [Craig S. Knox, Matthew T. Vaughan, Andrew D. Burnett, Mannan Ali, Satoshi Sasaki, Edmund H. Linfield, Alexander Giles Davies, and Joshua R. Freeman (2022): Dataset associated with Effects of Structural Ordering on IR Active Vibrations Within Bi2(Te(1-x)Sex)3. [Dataset]. https://doi.org/10.5518/1219] Related publication: [Effects of Structural Ordering on IR Active Vibrations Within Bi2(Te(1-x)Sex)3, By; Craig S. Knox, Matthew T. Vaughan, Andrew D. Burnett, Mannan Ali, Satoshi Sasaki, Edmund H. Linfield, Alexander Giles Davies and Joshua R. Freeman, Physical Review B, 2022, In preparation.] Contact: [C.S.Knox@leeds.ac.uk] 2. TERMS OF USE --------------- [This dataset is licensed under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/.] 3. PROJECT AND FUNDING INFORMATION ---------------------------------- Title: [HyperTHz] Funding organisation: [UKRI] Grant no.:[EP/P021859/1] Title 2:[NAME] Funding organisation: [UKRI] Grant no.:[EP/P021859/1] Title 3:[EXTREME-IR] Funding organisation: [European Union’s Horizon 2020 research and innovation program] Grant no.:[964735] Title 4:[Dynamics, Control and Energy Transfer at Terahertz Frequencies.] Funding organisation: [UKRI] Grant no.: [EP/P007449/1] Title 5:[Sir Henry Royce Institute - Leeds Equipment] Funding organisation: [Henry Royce Institute] Grant no.:[EP/P022464/1] Titel 6:[Sir Henry Royce Institute - recurrent grant] Funding organisation: [Henry Royce Institute] Grant no.: [EP/R00661X/1] 4. CONTENTS ----------- File listing [The data as seen in the paper is collected in 5 Origin projects (Fig_1_and_Fig_5.opju, Fig_2.opju, Fig_3_and_Table_1.opju, Fig_4.opju, and Fig_6.opju), where each graph is labelled according to the figure part it represents. In addition, Fig_2.opju contains the Raw XRD data used for each sample, and Fig_1_and_Fig_5.opju contains the results of fitting the conductivity spectra to equation 2 in the manuscript. Those conductivity spectra and their fits are found as ASCII .dat files under the "Raw_Spectra" folder. The "Two_Carrier_Fitting_data" contains ASCII .txt files containing the Hall resistance and two-carrier fits used to extract the data in Table 1. Within these folders, the samples are labelled by growth-chamber run-number, detailing the date on which the samples were grown. The relevant alloy fractions are as follows: MBE20210302 - Bi2Te3, x=0 MBE20210312 - Bi2Se3, x=1 MBE20210318 - x=0.35 MBE20210324 - x=0.33 MBE20210326 - x=0.48 MBE20210415 - x=0.52 MBE20210416 - x=0.57 MBE20210419 - x=0.87 The Folder "DFT_Calcs" contains input and output files for calculations performed to support the paper. In this compressed file you will find three folders Bi2Se3, Bi2Te3 and Bi2SeTe2 which contain the calculations belonging to each material system calculated for the paper Within each folder there are then 3 more folders Opt, Phonopy and Anharm The majority of folders contain VASP input and output files, therefore Input files are INCAR/KPOINTs/POSCAR and Relevant OUTPUT files include vasprun.xml/OUTCAR/OSZICAR etc etc for more information on VASP file formats please consult the VASP manual POTCARS have not been included per VASP license restrictions but standard PAW POTCARS supplied with VASP 5.4.4. were used for all calculations. The OPT folder contains the input and output files for a geometry optimisation of a conventional cell form of the material. Initial positions were downloaded from the materials project in cif format and cif2cell was used to generate the conventional cell in POSCAR format. The Phonopy folder contains the phonon calculations of the material. The main folder contains a number of files and subfolders The DISP-XXX folders where XXX is a number contain the single point energy calculations for each of the displaced structures The Born-111 folder contains a calculation to determine the BORN charges for the undisplaced structure which would be required to calculate IR intensity Within the Phonopy folder itself: phonopy_disp.yaml contains information about the displaced structures with the displacement written in Cartesian coordinates. POSCAR is the optimised structure that phonopy uses to calculate the displaced structures POSCAR-XXX are the displaced structures where XXX is a number SPOSCAR is the undisplaced supercell which in this case is the same as POSCAR FORCE_SETS is the force constant matrix determined after the single point energies of the displaced structures are performed There are then two more subfolders within the Phonopy folder called nopa and pa pa contains the phonopy calculated results projected back onto the primitive unit cell nopa contains the phonopy calculated results for the conventional cell without projection In both folders there is: a phonopy configuration (*.conf) file which was used to generate the phonopy output files a phonopy.yaml file containing a summary of structures used in the calculations in this folder a qpoints.yaml file which contains the frequencies calculated at the Gamma-point relevant to the IR and Raman spectra a thermal_properties.yaml which contains information of the thermal properties of material determined using Phonopy for more information about the *.yaml and FORCE_SETS files and there structure consult the Phonopy documentation at https://phonopy.github.io/phonopy/ In each of the Anharm folders there are two sub-folders labelled mode18 and mode19 Mode18 is the A1g Raman active mode Mode19 is the E1g IR active mode Each of these folders contains 31 sub-folders (labelled 001..031) and 31 POSCAR-XXX files. The POSCAR files are the structures determined along the vibrational coordinate and each folder is the single point energy calculation of the associated structure ModeMap.csv contains information about the displaced structures ExtractTotalEnergies.csv contains information about the energy of each structure ModeMap_PostProcess.csv combines the information in the two files allowing the calculated potentials to be easily plotted Potentials were then fitting using SciPy to a 6-order polynomial and these were used as input for the 1DSchrodingerSolver included as part of the ModeMap tools. As such each folder has an input.dat file which is the input to the Schrodinger Solver along with several output dat files. The most relevant file for this work is the t-vs-omega.dat which contains the Effective (renormalised) harmonic frequencies as a function as temperature. However, all files outputted by this program including calculated eigenvalues (eigenvalue.dat), eigenvectors (eigenvector.dat) and wavefunctions (wavefns.dat) have been included for completeness.] 5. METHODS ---------- [The data within Fig_2.opju was collected using a Bruker X-Ray diffractometer. Except for MBE20210302, all samples were scanned over the range shown in the paper, with a 2 second accumulation time while aligning to the 41.69 degree peak arising from the c-plane sapphire substrate. MBE20210302 was scanned from 5 to 85 degrees, with an 8s accumulation time, also aligned to the same sapphire peak. The data within Fig_3_and_Table_1.opju, as well as the Two_Carrier_Fitting_data folder were taken in a continuous flow Oxford Instruments He cryostat, in a van der Pauw configuration with a source-drain bias current of 1 uA. The THz time domain spectroscopy measurements were undertaken between 3 and 300 K in a continuous flow He cryostat. Both quartz and transparent polymethylepentene (TPX) windows were used in this study, with negligible effects on the observed spectra, aside from a weak resonance at ~4 THz from the quartz windows. The TPX windows do not show this resonance. The sample to be measured, along with a bare sapphire reference, were then mounted co-axially on the cold finger of the cryostat, which was subsequently evacuated and cooled to the required temperature. The time-domain signal was then acquired using 20 fs pulses from a Ti-Sapphire laser, a delay stage and two LT-GaAs-on quartz photo-conductive antennas, with a spectral range of 0.5 - 4.5 THz. The time-domain data is then trimmed (with a boxcar window) to remove unwanted Fabry-Perot reflections and zero-padded by 5 ps in either direction before a Fourier transform was taken. The complex transmittance, is then defined as the ratio between the complex Fourier transforms of the sample and the reference. Equation 1 within the paper can then be used to find the complex conductivity of the sample. The complex conductivity spectra acquired in this manner can then be fitted to equation 2 within the manuscript to obtain the relevant material parameters. DFT calculations were performed using VASP version 5.4.4 Phonon calculations were performed using Phonopy version 2.9.1 using VASP as the computational Engine Deformations along a phonon mode trajectory were generated using the ModeMap tool by JMSkelton and Colleagues which can be found here https://github.com/JMSkelton/ModeMap Single point Energy calculations of the generated structures were performed using VASP and additional scripts from ModeMap package were used to extract the energies along the phonon mode trajectory. ]