2667
Fitting of Hanle spin precession data in bilayer and multilayer graphene yields a spin relaxation time of ~ 125 - 250 ps and a spin diffusion length of 1 . 7 - 1 . 9 mu m at room temperature .
 Chemical: graphene
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: graphene