Heat_Capacity.dat

Columns 1, 3, 5, 7, 9 , 11 = Temperature (Kelvin)
Columns 2, 4, 6, 8, 10, 12 = Sample Heat Capacity (Joules per Kelvin per mole)

Applied magnetic field strength (\mu_{0}H):
Columns 1, 2 = 0 T
Columns 3, 4 = 1 T
Columns 5, 6 = 3 T
Columns 7, 8 = 5 T
Columns 9, 10 = 7 T
Columns 11, 12 = 9 T

The magnetic contribution to the heat capacity presented in the paper is derived by fitting the zero-field heat capacity to a phonon model (see text, and the 
references therein) and subtracting this from the sample heat capacity.



Linear_Susceptibility.dat

Column 1 = Temperature (Kelvin)
Column 2 = Linear susceptibility (meters cubed per mole)

Measurements are recorded in a quasistatic applied magnetic field \mu_{0} = 0.1 T.



AC_Susceptibility.dat

Columns 1, 4, 7 = Temperature (Kelvin)
Columns 2, 5, 8 = In phase susceptibility (meters cubed per mole)
Columns 3, 6, 9 = Out of phase susceptibility (meters cubed per mole)

alternating current frequency:
Columns 1-3 = 116 Hz
Columns 4-6 = 539 Hz
Columns 7-9 = 1500 Hz



Differential_Susceptibility

Columns 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27 = Applied magnetic field ($\mu_{0}H$) (Tesla)
Columns 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, = Magnetization (arbitrary units)

Temperature:
Columns 1, 2 = 0.53 K
Columns 3, 4 =0.65 K
Columns 5, 6 = 0.85 K
Columns 7, 8 = 1.045 K
Columns 9, 10 = 1.085 K
Columns 11, 12 = 1.205 K
Columns 13, 14 = 1.308 K
Columns 15, 16 = 1.38 K
Columns 17, 18 = 2.14 K
Columns 19, 20 = 2.6 K
Columns 21, 22 = 3 K
Columns 23, 24 = 3.4 K
Columns 25, 26 = 3.8 K
Columns 27, 28 = 4.2 K



Electron_spin_resonance_1.dat

Columns 1, 3, 5, 7, 9, 11 = Applied magnetic field ($\mu_{0}H$) (Tesla)
Columns 2, 4, 6, 8, 10, 12 = Differential Transmission Intensity (dI/dH) + a constant offset (arbitrary units)

All measurements were performed with 435.2 GHz microwaves.

Temperature:
Columns 1, 2 = 3.3 K
Columns 3, 4 = 5 K
Columns 5, 6 = 10 K
Columns 7, 8 = 20 K
Columns 9, 10 = 50 K
Columns 11, 12 = 100 K



Electron_spin_resonance_2.dat

Columns 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21 = Applied magnetic field ($\mu_{0}H$) (Tesla)
Columns 2, 4, 6, 8, 10, 12, 14, 16, 18. 20, 22 = Differential Transmission Intensity (dI/dH) + a constant offset (arbitrary units)

Measurements recorded at 3.5 K (and 3.31 K for the 435.2 GHz measurement)

Frequency:
Columns 1, 2 = 203.2 GHz
Columns 3, 4 = 209.6 GHz
Columns 5, 6 = 217.6 GHz
Columns 7, 8 = 222.4 GHz
Columns 9, 10 = 304.8 GHz
Columns 11, 12 = 333.6 GHz
Columns 13, 14 = 406.4 GHz
Columns 15, 16 = 416 GHz
Columns 17, 18 = 435.2 GHz
Columns 19, 20 = 609.6 GHz
Columns 21, 22 = 633.6 GHz





Muon_Spin_Rotation.dat

Columns 1, 4, 7, 10, 13, 16 = Time (microseconds)
Columns 2, 5, 8, 11, 14, 17 = Asymmetry (arbitraty units)
Columns 3, 6, 9, 12, 15, 18 = Error in asymmetry (arbitrary units)

Temperature:
Columns 1-3 = 1.517 Kelvin
Columns 4-6 = 2.005 Kelvin
Columns 7-9 = 5.220 Kelvin
Columns 10-12 = 10.782 Kelvin
Columns 13-15 = 0.0199 Kelvin
Columns 16-18 = 0.0190 Kelvin

The asymmetry vs. time model descibed in the supplemental information may be used to obtain the fitted curves displayed in the muon spin-roation figure. 


Muon_Spin_Rotation2.dat

Coulmn 1 = Temperature (Kelvin)
Column 2 = \lambda_s (MHz)
Column 3 = Error in lambda_s (MHz)


Muon_Spin_Rotation3.dat

Coulmn 1 = Temperature (Kelvin)
Column 2 = \omega/(2\pi)(MHz)
Column 3 = Error in \omega/(2\pi)(MHz) (MHz)

DFT data

Files are organised as follows:

3-link.models: contains 3-link model CASTEP output.
	       contains subdirectories:
	       		up: `up' structure
			down: `down' structure
	       both of which contain the subdirectories:
	       	       	AFM: AFM output
			FM: FM output
	       files in the output directories:
	       *.usp: on-the-fly psuedopotential
	       *.bib, *.castep: CASTEP output
	       *.cell, *param: CASTEP cell and parameter input
	       *.xsf: spin data extracted from raw binary output
	       Ni_$foo: script file

2-link.models: contains 2-link model CASTEP output
	       contains subdirectories:
	       		up_symmetric: `up symmetric' structure
	       		up_asymmetric: `up asymmetric' structure
	       		down_symmetric: `down symmetric' structure
	       		down_asymmetric: `down asymmetric structure
	       all of which contain the subdirectories:
	       	      	AFMw: AFMw output
			AFMs: AFMs output
			FM: FM output
	       files in the output directories:
	       *.usp: on-the-fly psuedopotential
	       *.bib, *.castep: CASTEP output
	       *.cell, *param: CASTEP cell and parameter input
	       Ni_$foo: script file

	       the AFMs/AFMw/FM directories for the down_asymmetric case
	       contain subdirectories:
	                r1, r2: reruns of the calculation to check results
		        for_xsf: rerun generating a *.xsf file for spin plots
	       the AFMs/AFMw directories for the down_asymmetric case
	       contain a subdirectory:
	       	        convergence: contains results of convergence checking 
			runs:
			1x1x1, 4x4x4: MP grid convergence
			GS=*: grid scaling convergence
			FINE, EXTREME: basis cut-off convergence