qdsquid-dataplot

A collection of MATLAB functions that parse and fit data from a Quantum Design MPMS 3 and MPMS XL SQUID magnetometers.

Setup

The folder containing these scripts should be added to your MATLAB path. This can be done by clicking the Set Path button under the Home tab. See this for more details.

Usage

Datafiles (.dat) are parsed by classes whose constructor arguments are filenames or lists of filenames. Constructors called without arguments parse all .dat files in the current directory. Classes that typical users will instantiate are: ACData, MagnetizationData, SusceptibilityData, and WaveformData. The corresponding object properties contain raw, parsed, and potentially fitted data and the object methods perform routine operations on these data (currently: fitting, exporting). Each class instance of ACData and WaveformData corresponds to one model fit of the supplied dataset(s). SQUID versions and measurement modes are automatically detected and currently supported types are: (MPMS 3) AC, DC, and VSM (MPMS XL) AC, DC, and RSO.

Input files

Datafile headers are parsed and used to perform conversions and corrections to the data. These fields can be set in the 'Sample Properties' window of MultiVu or manually using a text editor. They should be set before using this code. Their convention differs depending on the type of magnetometer used:

For all magnetometers

• Mass: Sample mass in mg

For MPMS 3 data

• Molecular Weight: Sample molecular weight in g mol^-1
• Volume: Mass of eicosane in mg
• Size: Sample molar diamagnetism

For MPMS XL data

• Area: Mass of eicosane in mg
• Length: Sample molecular weight in g mol^-1
• Shape: Sample molar diamagnetism

τ model classes

ACData

Parses and fits standard AC susceptibility data to a generalized Debye model.

WaveformData

Performs the Fourier transform on DC, RSO, or VSM moment data and fits the resulting susceptibilities to a generalized Debye model. Details about this method can be found in: https://arxiv.org/abs/1907.05962

Export format

Data tables are exported to .xlsx files using objectName.writeData(). Sheet 1 contains objectName.Parsed. τ model classe also contain sheets 2, 3, and 4 which correspond to objectName.Fits, objectName.Errors, and objectName.Model.

Caveat emptor

The current release of this code package does little in the way of error handling (e.g. class/data mismatch). Therefore, the occassional file parsing error or user oversight will most likely be met with a potentially unhelpful MATLAB error message.

Example usage

Example files can be found in the examples directory

(1) AC susceptibility

Data import:

>> Er_COT_I_THF2_AC = ACData('171124 - Er(COT)I(THF)2 - ACvsF.dat')
171124 - Er(COT)I(THF)2 - ACvsF.dat missing header information (replacing with default values):
    'EicosaneMass'

Fitting DebyeData with GeneralizedDebye fit type.

Er_COT_I_THF2_AC =

  ACData with properties:

      FitType: 'GeneralizedDebye'
         Fits: [18×5 table]
       Errors: [18×9 table]
        Model: [1800×4 table]
    DataFiles: [1×1 SQUIDDataFile]
       Parsed: [540×8 table]

View subset of fits:

>> Er_COT_I_THF2_AC.Fits(1:5, :)

ans =

 5×5 table

   TemperatureRounded      Xt        Xs        alpha        tau
   __________________    ______    _______    _______    _________

            5            2.1409    0.14513    0.14138    0.0023311
          5.5            1.9509    0.13367    0.14192     0.002325
            6            1.7919    0.12439    0.14122    0.0023092
          6.5            1.6565    0.11631    0.13975    0.0022813
            7            1.5398    0.10945    0.13697    0.0022367

Export data:

>> Er_COT_I_THF2_AC.writeData
Wrote data to Er_COT_I_THF2_AC.xlsx

(2) Long timescale waveform

Data import:

>> Er_hdcCOT2_waveform = WaveformData()
SQUIDData constructor called with no arguments, reading all .dat files in current directory.
Fitting DebyeData with GeneralizedDebye fit type.

Er_hdcCOT2_waveform =

  WaveformData with properties:

      Spectra: [125151×4 table]
      FitType: 'GeneralizedDebye'
         Fits: [5×5 table]
       Errors: [5×9 table]
        Model: [500×4 table]
    DataFiles: [5×1 SQUIDDataFile]
       Parsed: [45×5 table]

View subset of calculated impedance data:

>> Er_hdcCOT2_waveform.Parsed(1:5, :)

ans =

  5×5 table

    TemperatureRounded    Frequency     ChiIn     ChiOut       phi
    __________________    __________    ______    _______    ________

            2             0.00013011    5.5083    0.26636    0.048317
            2             0.00026003    5.4157    0.45522    0.083857
            2             0.00051861    5.1768    0.83523     0.15996
            2              0.0010334    4.6218     1.3189     0.27797
            2              0.0020498    3.7456      1.612      0.4064