Exchange-bias effect at La0.75Sr0.25MnO3/LaNiO3 interfaces

J. C. ROJAS S´ANCHEZ, ; B. NELSON-CHEESEMAN ; M- GRANADA; E. ARENHOLZ; L.B. STEREN

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2012 vol. 85 p. 94427 - 94431

1098-0121

We show that ferromagnetic/paramagnetic La0.75Sr0.25MnO3/LaNiO3 multilayers present an unexpectedmagnetic exchange-bias effect (EBE), observed in field-cooled magnetization loops. The exchange-bias fieldand the enhancement of the coercivity vanish around 50 K. We demonstrate that the oxidation state of the Niand Mn cations changes from Mn3+-Ni3+ to Mn4+-Ni2+ in the layers close to the interface probed by x-rayabsorption spectroscopy measurements. The variation of the valence states is accompanied by a change in themagnetic behavior of the cations at the La0.75Sr0.25MnO3/LaNiO3 interface, possibly giving rise to the formationof magnetic or magnetically frustrated regions that may pin the ferromagnetic La0.75Sr0.25MnO3 layers and explainthe EBE.