Fig2a.dat - Contains the data shown for Figure 2 (a). The file consists of 2 columns titled: T (K) and Chi (m3/mol). These represent the temperature (X) in kelvin and magnetic susceptibility (Y) in metres cubed per mole.

Fig2b.dat - Contains the data shown for Figure 2 (b). The file consists of 2 double columns of DC-field magnetisation in bohr magnetons per ion (Y) versus applied magnetic field in tesla (X) for temperatures of 0.5, 1.8, 4 and 10 kelvin.

Fig2b_inset.dat - Contains the data shown for the inset of Figure 2(b). The file consists of 2 double columns of the 1st (dM/dH) and 2nd (d2M/dH2) derivatives of the DC-field magnetisation (Y) plotted against the magnetic field (X) in tesla.

Fig2c.dat - Contains the data shown for Figure 2 (c). The file contains 2 columns showing pulsed field magnetisation (Y) plotted against applied magnetic field in tesla (X) at 0.36 K.

Fig2d.dat - Contains the data shown for Figure 2 (d). The file contains 2 columns showing the 1st differential (Y) of the 0.36 K pulsed field magnetisation, in Fig 2 (c), as a function of magnetic field (X).

Fig3a.dat - Contains the data shown for Figure 3 (a). The file contains 2 double columns showing the single-crystal magnetisation (Y) measured as a function of applied magnetic field (X) for the field applied parallel (II) and perpendicular (perp) to the unique crystallographic c-axis (z).

Fig3b.dat - Contains the data shown for Figure 3 (b). The file contains 2 double columns showing the 2nd differential (Y) of the single-crystal magnetisation as a function of applied magnetic field (X) with the field applied parallel (II) and perpendicular (perp) to the unique crystallographic c-axis (z).

Fig4a - Full data can be accessed at https://www.isis.stfc.ac.uk/Pages/Data-Policy.aspx with the DOI 10.5286/ISIS.E.RB1810129 

Fig4b.dat - Contains the data shown for Figure 4 (b). The file contains 3 triple columns of the energy transfers (X), counts (Y) and error (Z) on the counts for inelastic neutron scattering data at 1.8, 4 and 7 kelvin temperatures at ISIS RAL, UK. The data is a cut over all |Q|-space and has a 12 kelvin background subtracted. Full data can be accessed as described in the above Fig4a text.

For Fig. 5 we plot column 2 (spectral intensity) against column 4 (field shift).  The plots have been normalized such that the maximum spectral intensity is 1.

For Fig. 6 we plot column 7 (HWHM1) against column 1 (applied field B).  Note that in the 
data files we specify instead the HWHM rather than the FWHM so these values differ by a factor of 1/2 from those included in the plot.  The data below B=4.4 T is fitted to a constant value which is 2.02 mT.  The data above B=4.4 T were fitted to a straight line that was constrained to agree with the constant value fit at B=4.4 T.  The straight line has equation y=0.536*(x-4.4)+2.02.  The fits were made using the T=0.02 K data and are shown overlaid on the T=0.75 K data as a guide to the eye.

Fig7a.dat - Contains the data shown for Figure 7 (a). The file contains 4 double columns showing frequency-dependance of the ESR transmission spectrum (Y), at temperature of 30 kelvin, measured against applied magnetic field (X) for baseline frequencies of 406, 295, 203 and 102 Giga-Hertz. 

Fig7b.dat - Contains the data shown for Figure 7 (b). The file contains 5 double columns, 4 of which show frequency-dependance of the ESR transmission spectrum (Y) at 3 K measured against applied magnetic field (X) for four baseline frequencies of 403, 324, 203 and 102 Giga-Hertz. One double column shows a simulation of the 324 GHz transmission spectrum (Y) against field (X) to demonstrate how well the simulations capture the data.

Fig7c.dat - Contains the data shown for Figure 7 (c). The file contains 13 double columns of the ESR resonant frequencies (Y2) in Giga-Hertz against field (X1) making us the first double column and their respective fits (Y2) plotted against applied magnetic field (X1) making up the second. Resonances are for simulations with the field parallel the the unique crystallographic c-axis (II z) and perpendicular to it (perp z) as well as the half-field transitions. End-chains resonances are also included. See manuscript for further details.

Fig8.dat - Contains the data shown for Figure 8. The file contains energy level transitions in kelvin for the field parallel the the c-axis (E_z) and perpendicular (E_x) and how they develop with applied field dependant on magnetic quantum number mz = +1,0,-1.

Fig9a.dat - Contains the data shown for Figure 9 (a). The file contains 5 columns showing the position [X1 (column 1) and X2(column 4)] in millimeters (mm) and Total (Y1), subtracted (Y2 - sub) and background (Y3 column 5 - bkd) raw SQUID responses in electromagnetic units (emu) for data in an applied magnetic field of 0.1 tesla.

Fig9b.dat - Contains the data shown for Figure 9 (b). The file contains 4 columns showing the position (X1) in millimeters (mm) and Total (Y1), subtracted (Y2 - sub) and background (Y3 - bkd) raw SQUID responses in electromagnetic units (emu) for data in an applied magnetic field of 4.0 tesla.

Fig9c.dat - Contains the data shown for Figure 9 (c). The file contains 4 columns showing the position (X1) in millimeters (mm) and Total (Y1), subtracted (Y2 - sub) and background (Y3 - bkd) raw SQUID responses in electromagnetic units (emu) for data in an applied magnetic field of 6.0 tesla.

Fig9d.dat - Contains the data shown for Figure 9 (d). The file contains 2 columns showing the magnetic field (X) in tesla (T) and the raw SQUID responses (Y) in electromagnetic units (emu) for data collected at a temperature of 0.5 kelvin.

Fig10a & Fig10b - Full data can be accessed at https://www.isis.stfc.ac.uk/Pages/Data-Policy.aspx with the DOI 10.5286/ISIS.E.RB1810129

Fig11a_upper.dat - Contains the data shown for the upper panel of Figure 11 (a). The file contains one column (X) containging energy transfer at a 1.46 meV rep-rate and four pairs of double columns that designate counts (Y) and error (Z) for the temperaures 1.8, 4, 7 and 12 kelvin. The data is a cut over all |Q|-space. Full data can be accessed as described in the above Fig4a text.

Fig11a_lower.dat - Contains the data shown for the lower panel of Figure 11 (a). The file contains one column (X) containging energy transfer at a 1.46 meV rep-rate and three pairs of double columns that designate counts (Y) and error (Z) for the temperaures 1.8, 4 and 7 kelvin. The data is a cut over all |Q|-space and has a 12 kelvin background subtracted. Full data can be accessed as described in the above Fig4a text.

Fig11b_upper.dat - Contains the data shown for the upper panel of Figure 11 (b). The file contains one column (X) containging energy transfer at a 2.19 meV rep-rate and four pairs of double columns that designate counts (Y) and error (Z) for the temperaures 1.8, 4, 7 and 12 kelvin. The data is a cut over all |Q|-space. Full data can be accessed as described in the above Fig4a text.

Fig11b_lower.dat - Contains the data shown for the lower panel of Figure 11 (b). The file contains one column (X) containging energy transfer at a 2.19 meV rep-rate and three pairs of double columns that designate counts (Y) and error (Z) for the temperaures 1.8, 4 and 7 kelvin. The data is a cut over all |Q|-space and has a 12 kelvin background subtracted. Full data can be accessed as described in the above Fig4a text.

Fig11c_upper.dat - Contains the data shown for the upper panel of Figure 11 (c). The file contains one column (X) containging energy transfer at a 3.71 meV rep-rate and four pairs of double columns that designate counts (Y) and error (Z) for the temperaures 1.8, 4, 7 and 12 kelvin. The data is a cut over all |Q|-space. Full data can be accessed as described in the above Fig4a text.

Fig11c_lower.dat - Contains the data shown for the lower panel of Figure 11 (c). The file contains one column (X) containging energy transfer at a 3.71 meV rep-rate and three pairs of double columns that designate counts (Y) and error (Z) for the temperaures 1.8, 4 and 7 kelvin. The data is a cut over all |Q|-space and has a 12 kelvin background subtracted. Full data can be accessed as described in the above Fig4a text.

Fig12_*K_data_fit.dat contain the data and fits for the resepective temperatures as shown in Fig. 12.

Fig13_lambda.dat contains the values of lambda seen in Fig. 13.