https://doi.org/10.1140/epjb/e2007-00218-0
Effect of Ta5+ substitution for Mn on the ground state of La0.67Ca0.33MnO3
1
XS & CGS, Materials Science Division, Indira Gandhi Centre For Atomic Research, Kalpakkam, 603102, Tamil Nadu, India
2
Institute of Metallic Materials, IFW Dresden, Postfach 270116, Dresden, 01171, Germany
Corresponding author: a slaxmi73@gmail.com
Received:
12
April
2007
Revised:
28
June
2007
Published online:
10
August
2007
We report the charge state modification effects at the Mn site on the ground
state properties of colossal magnetoresistive manganites. Ta5+
substitution results in an appreciable increase in the lattice parameters
and unit cell volume due to increased Mn3+ concentration. The
ferromagnetic-metallic ground state modifies to a cluster glass insulator
for . The reduction in the transition temperatures with
increasing x is ∼39 K/at.%. Besides the modification of majority carrier concentration due to increased Mn3+ concentration and enhanced local structural effects, the local
electrostatic potential of the substituent seems to contribute to the
unusually strong reduction of the transition temperatures of the compounds.
Thermo magnetic irreversibility just below Curie temperature (Tc),
non-saturation of magnetization, two distinct magnetic transitions in ac
susceptibility in an appropriate static field: close to Tc and other at
low temperature (the spin freezing temperature (Tg)) and non-stationary
dynamics with a characteristic maximum in the magnetic viscosity close to
Tg confirm a cluster glass state for
. These results
find additional support from a linear low temperature magnetic specific heat
of x = 0.10 with a characteristic broad maximum close to Tg.
PACS: 75.47.Lx – Manganites / 75.50.Lk – Spin glasses and other random magnets / 75.40.Cx – Static properties / 75.40.Gb – Dynamic properties
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007