Interfacial spin glass state and exchange bias in manganite bilayers with competing magnetic orders

The magnetic properties of manganile bilayers composed of G-type antiferromagnetic (AFM) SrMnO sub(3) and double-exchange ferromagnetic (FM) La sub(0.7) Sr sub(0.3) MnO sub(3) are studied. A spin-glass state is observed as a result of competing magnetic orders and spin frustration at the La sub(0.7) Sr sub(0.3) MnO sub(3)/SrMnO sub(3) interface. The dependence of the irreversible temperature on the cooling magnetic field follows the Almeida-Thouless line. Although an ideal G-type AFM SrMnO sub(3) is featured with a compensated spin configuration, the bilayers exhibit exchange bias below the spin glass freezing temperature, which is much lower than the Neel temperature of SMO, indicating that the exchange bias is strongly correlated with the spin glass state. The results indicate that the spin frustration that originates from the competition between the AFM super-exchange and the FM double-exchange interactions can induce a strong magnetic anisotropy at the La sub(0.7) Sr sub(0.3) MnO sub(3)/SrMnO sub(3) interface.