Magnetic Properties of La1-xSrxMnO3 Nanocrystals Embedded in A Mesoporous Silicate

Abstract

AbstractWe have prepared the diluted assemblies of La1-xSrxMnO3 (x = 0, 0.05, 0.15 and 0.175) nanocrystals (ø ∼ 2∼3 nm) embedded in amorphous SiO2 to clarify the nano-magnetism of both the antiferromagnetic and ferromagnetic La1-xSrxMnO3. All the samples of x = 0, 0.05, 0.15, and 0.175 exhibited superparamagnetism with the blocking temperature of ∼40 K. Except the hump at ∼40 K, the antiferromagnetic x = 0 and 0.05 samples showed simply paramagnetic-like characteristics in both the temperature dependent dc and ac susceptibilities. The ferromagnetic x = 0.15 and 0.175 samples demonstrated complicated characteristics in the temperature dependent susceptibilities. The samples indicated antiferromagnetic and ferromagnetic behavior above ∼50 K and ∼100 K, respectively. The field dependent magnetization is consistent with the predictions of systems having randomly oriented and noninteracting fine particles (ø ∼2∼3 nm). For the ferromagnetic La1-xSrxMnO3 nanocrystals, the antiferromagnetism at crystal surfaces suppressed largely the ferromagnetism in bulk.