MAGNETISM ELECTRON TRANSPORT MAGNETORESISTIVE LANTHANUM CALCIUM MANGANITE

160 Appendix A
(T/T C - 1) γ . From these data (Figure A- 4) γ = 1.17 ± 0.02 is estimated. The plot
of 1/χ vs. T should be close to linear for high temperatures.
2 )
M 2 × |T/T C - 1| -2 β (µ B
6.0
5.0
4.0
3.0
2.0
1.0
SrRuO 3 Crystal Scaled Arrott Plot
T < T C
T > T C
0.0
0 500 1000 1500 2000 2500
H/M × |T/T - 1|
C -γ (kOe/µ )
B
The M(H, T) data can be replotted using the scaling hypothesis [90] with
β = 0.36 and γ = 1.17. According to the hypothesis, the magnetic equation of
state in the critical region depends only on the scaled variables H/|T C /T - 1| β+γ
and M/|T C /T - 1| β . A plot of the scaled M 2 and scaled H/M, shown in
Figure A- 5, will then have only two curves: one branch for the T < T C data
and another for T > T C . Not all the curves fit on a single line, this is due to
the apparent change in β as discussed above.
β = 0.36
γ = 1.17
T C =163.2K
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.
The critical isotherm (T = T C ) should obey the relation M δ ∝ H, where
according to the scaling relation δ = γ/β + 1. From the previously measured
values of β and γ, the exponent δ is therefore expected to be 4.3 ± 0.5. This is
in good agreement with the measured value (Figure A- 2) δ = 4.2 ± 0.2.