I have been told when making transport measurements of graphene it is usually placed in a cryostat and cooled to ~ 4K. However I cannot find any sources that back this up and don't fully understand why it is done in the first place. My thoughts are that it is to measure the carrier mobility with minimal the scattering effects. But is it not more beneficial to measure this at room temperature as this is the most likely situation for graphene based devices. Also, is there another situation when it is suitable to cool graphene to cryogenic temperatures?