MAGNETISM ELECTRON TRANSPORT MAGNETORESISTIVE LANTHANUM CALCIUM MANGANITE

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Figure 7-11. Fitting parameter σ H as a function of temperature in a La 0.67Ca 0.33MnO 3
film for T < T C. The solid line shows the best fit to the data using a critical
exponent of 0.7. 146
Figure 7-12. Magnetoresistance of La 0.67Ca 0.33MnO 3 film at 262 K ≈ T C. The solid line
shows the fit (for the full data on a linear scale) using the indicated equivalent
circuit. 149
Figure A- 1. Magnetization at 5 K of SrRuO 3 single crystal along several
crystallographic directions showing strong cubic but not uniaxial
magnetocrystalline anisotropy. Inset shows the full hysteresis loop of the single
crystal data along with that of a polycrystalline pellet for comparison. 155
Figure A- 2. Arrott Plot of SrRuO 3 single crystal along easy [110] direction. Inset,
critical isotherm (T = 163K ≈ T C) on a log scale fit to M δ ∝ H with δ = 4.2. 1 5 7
Figure A- 3. Zero field magnetization M 0 of SrRuO 3 single crystal along easy [110]
direction. Solid line shows the fit to M 0(T ) ∝ (1 - T /T C) β with β = 0.36. Inset
showing the same data on a log plot. The critical exponent β appears to change
from Heisenberg-like β = 0.39 near T C to Ising-like β = 0.32 as T decreases. 158
Figure A- 4. Zero field inverse susceptibility 1/χ 0 of SrRuO 3 single crystal along
easy [110] direction. Solid line shows the fit to 1/χ 0(T ) ∝ (1 - T /T C) γ with γ =
1.17 and T C = 163.2 K. The inset shows the same data on a log plot. 159
Figure A- 5. Scaled Arrott Plot of SrRuO 3 single crystal along easy [110] direction
with β = 0.36 and γ =1.17. Symbols are the same as those used in Figure A- 2.160
Figure A- 6. Magnetization as a function of temperature of SrRuO 3 single crystal
along easy [110] direction. Inset shows the approximate T 2 dependence of the
magnetization. 161
Figure A- 7. Inverse magnetic susceptibility (1/χ = M /H ) at H = 10 kOe of
polycrystalline SrRuO 3 compared to the single crystal data from Figure A- 4.
The solid line is the straight-line fit with T C = 165K which demonstrates the
slightly positive curvature of the data. 164
Figure A- 8. Variation of the T 3/2 parameter in fitting the magnetization data of single
crystal SrRuO 3 to M = M S (1 - AT 3/2 - BT 2 ) as the fitting range is increased. The
upper inset shows the correlation of the A and B parameters. In the region where
A is relatively stable (around T max = 60 K), A decreases as T max is lowered. The
symbols are the same as those used in Figure A- 9. 166
Figure A- 9. Variation of the T 2 parameter in fitting the magnetization data of single
crystal SrRuO 3 to M = M S (1 - AT 3/2 - BT 2 ) as the fitting range is increased. In
the region where B is relatively stable (around T max = 60 K), B increases as T max is
lowered. 167
Figure A- 10. Variation of the T 2 parameter in fitting the magnetization data of
single crystal SrRuO 3 to M = M S (1 - BT 2 ) as the fitting range is increased. The
parameter B for this fit is more stable and constant than that shown in Figure A-
8. Inset, variation of Θ 2 in a magnetic field. 169
Figure A- 11. Variation of A and B fitting parameters in the hypothetical case where
the true magnetization is given by T 3/2 and T 5/2 terms. 170
Figure B- 1 Heat capacity of SrRuO 3 cooled in zero field (zfc), in an 8 T magnetic
field, and in zero field after being magnetized (rem). Inset, difference between the
heat capacity measured after cooling in zero field with that in 8 T and the
remnant magnetized state. 174
Figure B- 2. Zero field heat capacity data fit with two free parameters, γ and β. Solid
line, including the T 3/2 contribution expected theoretically for spin waves (see
text). Dashed line, without any T 3/2 contribution. 175
Figure B- 3. The linear term of the heat capacity γ as a function of magnetic field.
Each circle is from a single c P,H datum between 4.3 and 5 K with phonons
subtracted: γ(H ) = (c P,H(T) - βT 3 )/T with β = 0.191 mJ/mol·K 4 . γ(H ) for each
square was determined by fitting 15-20 data points between 6 and 12 K to: c P,H(T)