Effect of spin and electron configuration of substituents for manganese on
charge transport in CMR manganites
Alexey G. Badelin*, Vladimir K. Karpasyuk, Andrey M. Smirnov, Fardin K. Ilyasov
Astrakhan State University, Astrakhan, Russia
*e-mail: [email protected]
The effect of electron configuration and spin moment of the ions in pared substitution of
2
4
(Me0.5
Me0.5
) for Mn3 on phase transition “semiconductor-metal” in manganites
2
6
3
4
2
4
2
10
2
8
2
La1c Sr c Mn1cx Mn c (Me 0.5 Me 0.5 ) x O 3 , where Me  Mg (2 p ) , Zn (3d ) or Ni (3d ) , and
4
4
10
Me  Ge (3d ) , has been investigated.
Figure 1 illustrates temperature dependences of the resistivity of manganites with c0.19 (a)
and c  0.30 (b), measured at magnetic field of 9.2 kOe (light symbols) and in the absence of
field (black symbols). As Figure 1(a) displays, substitution of Ni 2 for the half amount of Ge4
ions in manganite with the same value of Mn4 concentration (0.19 f.u.) leads to decrease of the
“metal-semiconductor” transition temperature ( Tms ). Comparison of the curves on figure 1(b)
make it possible to conclude that (Ni, Ge)-substituted manganites are characterized by essentially
higher Tms than analogous compositions with (Mg, Ge).
It is interesting to note that manganite La 0.8 Sr 0.2 Mn 0.9 Ni 0.1O 3 , with the same values of
substituent and Mn4 concentrations (0.1 and 0.30 f.u., correspondingly), has semiconducting
type of conductivity at T  100K . For La 0.70 Sr 0.30 Mn 0.90 (Zn 0.5 Ge 0.5 ) 0.10 O 3 manganite
T ms  300K .
a
b
Fig. 1. Temperature dependencies of the resistivity of manganites:
▲, Δ – La 0.81 Sr 0.19 Mn 0.90 ( Ni 0.5Ge 0.5 )0.10 O 3 ; ●, ○ – La 0.71 Sr 0.29 Mn 0.90 Ge 0.10 O 3 (a) and
▼,  – La 0.70 Sr 0.30 Mn 0.90 ( Ni 0.5Ge 0.5 )0.10 O 3 ; ■, □ – La 0.70 Sr 0.30 Mn 0.90 (Mg 0.5Ge 0.5 )0.10 O 3 (b)
Established regularities are interpreted in terms of double exchange with the allowing for
competing interactions, steric factors and formation of clusters [1,2].
This research was performed within the framework of the State order of the Ministry of
Education and Science of RF (project 334).
References
[1] Salamon M.B., Jaime M., “Rev. Mod. Phys.”, V.73, P. 583-628, 2001.
[2] Karpasyuk V.K., Badelin A.G., Estemirova S.Kh., Merkulov D.I., “Natural Sciences”,
No.4(49), P. 123-129, 2014.