Contrasting size-scaling behavior of ferromagnetism in La_0.67Ca_0.33MnO₃ films and La_0.67Ca_0.33MnO₃/CaRuO₃ multilayers Available to Purchase

Using La_0.67Ca_0.33MnO₃ (LCMO) and CaRuO₃ (CRO) as components, the single-layer films, bilayers, trilayers, and superlattices were fabricated on NdGaO₃ (110) substrates. These epitaxial structures show quite different Curie temperature (T_C) depending on the LCMO layer thickness (x), especially in the low x region. For LCMO films, T_C dramatically decreases with x and disappears below 3.2 nm, as previously reported. For LCMO/CRO (CRO/LCMO) bilayers, however, a smooth decline of T_C was observed, retaining a T_C near 50 K at 1.6 nm. More strikingly, for the multilayers with LCMO sandwiched between CRO, T_C is stabilized at ∼250 K even at x of 1.6 nm, before decreasing to 200 K at 0.8 nm. We ascribed these distinct behaviors to the LCMO/CRO interfaces, and a possible charge transfer from CRO to LCMO was suggested to play a vital role in stabilizing the ferromagnetism in ultrathin LCMO. This finding would shed some lights on the dead layer formation in ultrathin manganites and be significant in improving the performance of the related spintronic devices.