Barkhausen-like steps and magnetic frustration in doped La0.67−xAxCa0.33MnO3 ?A=Ce,Y?

G. ALEJANDRO; L.B. STEREN; A. CANEIRO; J. CARTES; E.E. VOGEL; P. VARGAS

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

American Physical Society

Año: 2006 vol. 73 p. 544271 - 544277

0163-1829

We present dc magnetization experiments performed on the doped, polycrystalline systemLa0.67−xAxCa0.33MnO3
A=Ce,Y. The ceramic samples have been obtained by the nitrate decomposition routeand structurally characterized by powder x-ray diffraction. Hysteresis loops reveal an exciting and nonrepetitivemultistep structure of Barkhausen-like jumps in the low fields region, up to 50 Oe. We discuss our resultsin terms of a collective response of magnetic moments pinned by frustration due to the competition amongdifferent exchange interactions present in the compounds. A simple Ising Hamiltonian with in-plane ferromagneticinteractions and randomly mixed off-plane interactions is introduced to model this hypothesis. Computersimulations based on this model allow us to reproduce most of the features observed in the hysteresis curves,allowing a qualitative understanding of the complex magnetic behavior of this family of manganites.