13498
Novel EuS nanocrystals containing paramagnetic Mn ( II ) , Co ( II ) , or Fe ( II ) ions have been reported as advanced semiconductor materials with effective optical rotation under a magnetic field , Faraday rotation .
 EuS, Mn ( II ), Co ( II ), Fe ( II )
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 EuS, Mn ( II ), Co ( II ), Fe ( II )