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Magnetic and superconducting properties of La2‑x Sr x CuO4 nanoparticles are systematically studied as a function of particle size and Sr doping. Through the magnetization and electron spin resonance measurements, it was found that the suppression of superconductivity and enhancement of ferromagnetism were observed simultaneously with decreasing particle size, which should be related to the uncompensated Cu2+ spins and oxygen defects due to the increasing role of finite size. On the other hand, although Sr doping will introduce more uncompensated spins to the La2‑x Sr x CuO4 nanoparticles, the low temperature ferromagnetism is reduced. The results suggest that the suppression of superconductivity and the appearance of ferromagnetism for the nanoparticles may be closely related to the destruction of antiferromagnetic correlation in CuO2 planes.

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