Intrinsic vs. extrinsic magnetic transitions in Sr3Ru2O7 films

In scientific research, both positive and negative results play crucial role in advancing the field. Negative results provide valuable insights that can guide future experiments and prevent repeated failures. Here we present our growth attempts of Sr₃Ru₂O₇ thin films using the hybrid molecular beam epitaxy. X-ray diffraction suggests nominally phase-pure films. A combination of magnetoresistance and magnetization measurements exhibits an onset of ferromagnetism at 170 K and 100 K along with a metamagnetic-like transition at 40 K. These results could initially be interpreted as intrinsic behavior of strain-engineered Sr₃Ru₂O₇ films. However, detailed microstructural analysis reveals intergrowths of Sr₂RuO₄, Sr₄Ru₃O₁₀, and SrRuO₃ phases, dispersed throughout the film. Our findings suggest that the Sr₃Ru₂O₇ films are likely paramagnetic, with the observed ferromagnetism arising from the Sr₄Ru₃O₁₀ and SrRuO₃ phases. Angle-dependent magnetoresistance measurements indicate that the transition below 40 K is consistent with the metamagnetic behavior reported in bulk single crystals of Sr₃Ru₂O₇, but with no accompanying in-plane anisotropy, suggesting the absence of electronic nematicity. Our results highlight the need for detailed microstructural analysis when interpreting strain-induced emergent properties in material systems susceptible to intergrowth.