Dresden 2006 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)

MA 20.3: Poster

Dienstag, 28. März 2006, 15:15–19:15, P1

Critical exponents of the ferromagnetic-paramagnetic phase transition of La_1−xSr_xCoO₃ thin films — •Thorsten Schwarz^1,2, Dirk Fuchs¹, and Rudolf Schneider¹ — ¹Forschungszentrum Karlsruhe, Institut für Festkörperphysik, D-76021 Karlsruhe — ²Universität Karlsruhe, Fakultät für Physik, D-76128 Karlsruhe

The critical exponents of the second-order ferromagnetic-paramagnetic phase transition of La_1−xSr_xCoO₃ thin films (0.1 ≤ x ≤ 0.6) and bulk materials are determined by magnetization measurements around the Curie temperature T_C (-0.05 ≤ є = (T-T_C)/T_C < 0.05) applying fields from 0 T to 5 T. The La_1−xSr_xCoO₃ thin films were grown on (001) (LaAlO₃)_0.3(Sr₂AlTaO₆)_0.7 (LSAT) single crystal substrates by pulsed laser deposition (PLD) and the bulk materials were made by standard solid state synthesis. T_C was determined by the derivative of the magnetization versus temperature, i.e., M vs. T, and M_S· (dM/dT)⁻¹ vs. T. In order to determine the critical exponents β, γ and δ the following three different techniques have been applied for the evaluation: i) Scaling-Plots, ii) Kouvel-Fisher and iii) the modified Arrott-Plots technique. Best results for the critical exponents β, γ and δ were obtained by the modified Arrott-Plots which are presented for thin films and bulk-materials.