Abstract
We report measurements of magnetothermopower and magnetoresistivity as a function of temperature on
Ru
Sr
2
Gd
2
−
x
Ce
x
Cu
2
O
10
+
δ
(
x
=
0.6
,
1
)
. In a magnetic field of
5
T
, the size of thermopower decreases significantly, whereas the normal-state resistivity decreases slightly, which behaves similarly to
Ru
Sr
2
Gd
1
−
x
La
x
Cu
2
O
8
(
x
=
0
,
0.1
)
. A significant decrease of thermopower for both samples could be attributed to the decrease of the spin entropy contribution associated with the carriers in the
Ru
O
2
layers, as the Ru moments are aligned with the magnetic field. It is also found that the nonmetallic temperature dependence at low
T
follows a variable range hopping process for both samples.