CeAl4 塊材隨溫度降至低溫出現鐵磁性及反鐵磁性，轉變溫度分別為TC = 6.2 K , TN = 3.2 K。使用雷射蒸鍍方法製作微粒樣品，並藉由控制工作壓力、雷射功率、基板溫度，使微粒的粒徑分布約在10 ~ 30 nm，經由X-ray 繞射圖確認成份組成與母材成份組成相同後，我們使用SOUID 測量2 K~ 300 K 的磁性。發現當尺寸縮小，反鐵磁性被抑制，且在6 K以下出現超順磁性，顯示微粒樣品仍為鐵磁性。我們測量在壓力0.02 torr下製作的微粒樣品，其居禮常數只有塊材的33%，顯示有部分的Ce離子轉變成不具磁性。 The bulk CeAl4 undergoes a ferromagnetic transition at TC = 6.2 K, follow by an antiferromagnetic ordering at TN = 3.2 K . The CeAl4 nanoparticles was fabricated by pulsed-laser deposition methods.By controlling carefully the conditions , including gas pressures , laser power and temperature of substrate, the CeAl4 nanoparticles were fabricated with sizes between 10 and 30 nm .No impurity phase can be detected by X-ray diffraction patterns . The magnetic behavior of nanoparticles have been measured by SQUID between 2 K and 300 K.We find that when the particles’ size was reduced , the antiferromagnetism will be depressed . A typical behaviors of superparamagnetism below 6 K . show that the sample remain on ferromagnetic state . The small curie constant of nanoparticles , which was fabricated under 0.02 torr He gas ,was about 33% of the bulk . This imply that a certain degrees of demagnetization of Ce ions in nanoparticles .
