A tricritical point is observed in the Nd1-x Srx Mn O3 (NSMO) (x=0.3, 0.33, and 0.4) manganites at x=0.33 which separates the first-order transition in NSMO-0.3 and second order transition in NSMO-0.4. The ferromagnetic transition of these compounds is further investigated by measuring magnetocaloric effect (MCE) and by applying a theoretical model based on Landau theory of phase transitions. Results indicate that the contributions to the free energy from the presence of correlated clusters are strongly influencing the MCE by coupling with the order parameter around the Curie temperature. © 2008 American Institute of Physics.

M. Pattabiraman

Department Of Physics

Kanikrishnan Sethupathi

G. Rangarajan

Curie temperature

Ferromagnetic materials

Free energy

Magnetic field effects

Manganites

Phase Transitions

FERROMAGNETIC TRANSITION

FIRST-ORDER TRANSITION

magnetocaloric effect (MCE)

Neodymium compounds

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IIT Madras

Tricritical point and magnetocaloric effect of Nd1−xSrxMnO3

Journal of Applied Physics

The magnetocaloric effect in single crystalline Nd0.7 Sr0.3 MnO3 is investigated by measuring the field-induced adiabatic change in temperature (Δ Tad) which reveals a single negative peak around 130 K well below the Curie temperature (TC =203 K). In order to understand this unusual magnetocaloric effect, we invoke the reported Mn55 spin-echo nuclear magnetic resonance, electron magnetic resonance and polarized Raman scattering measurements on Nd0.7 Sr0.3 MnO3. We show that this effect is a manifestation of a competition between the double exchange mechanism and correlations arising from coupled spin and lattice degrees of freedom which results in a complex ferromagnetic state. The critical behavior of Nd0.7 Sr0.3 MnO3 near Curie temperature is investigated to study the influence of the coupled degrees of freedom. We find a complicated behavior at low fields in which the order of the transition could not be fixed and a second-order-like behavior at high fields. © 2007 The American Physical Society.

Physical Review B - Condensed Matter and Materials Physics

Complex ferromagnetic state and magnetocaloric effect in single crystalline Nd0.7 Sr0.3 MnO3

Heteroepitaxial Growth of NSMO on Silicon by Pulsed Laser Deposition

Journal of Magnetism and Magnetic Materials

Magnetocaloric effect in Er- and Eu-substituted ferromagnetic La-Sr manganites

Physical Review B

Average lattice symmetry and nanoscale structural correlations in magnetoresistive manganites

Physical Review Letters

Tricritical Point and the Doping Dependence of the Order of the Ferromagnetic Phase Transition ofLa1−xCaxMnO3

Tricritical point and magnetocaloric effect of Nd1-x Sr x Mn O3

Journal	Journal of Applied Physics
ISSN	00218979
Open Access	No