MAGNETISM ELECTRON TRANSPORT MAGNETORESISTIVE LANTHANUM CALCIUM MANGANITE

164 Appendix A
1/χ 0 (emu -1 mol Gauss)
200
150
100
50
SrRuO 3 Polycrystal Inverse Susceptibility
Pellet
Single Crystal
0
150 200 250
Temperature (K)
300 350
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 straightline
fit with T C = 165K which demonstrates the slightly
positive curvature of the data.
A positive curvature persists in the plot of 1/χ vs. T (Figure A- 7) even at
higher temperature where it should be linear for a Curie-Weiss ferromagnet.
Such a curvature can be caused by a temperature independent term in the
susceptibility χ = χ Const + C/(T - Θ), where C/(T - Θ) is the Curie-Weiss
susceptibility and is always positive (T > Θ). A χ Const < 0 of about -4 × 10 -4 emu
G -1 mol -1 will provide the observed curvature, and has been independently
observed elsewhere [175]. The temperature independent term χ Const , should
contain a positive contribution due to Pauli paramagnetism. This can be
estimated from measurements of the linear term of the specific heat [176],
giving χ Pauli ≈ +4 × 10 -4 emu G -1 mol -1 . The Landau diamagnetism should be