Comment by phoenixstrike

Small. Imperfect contact, unplugged terminals, etc. These are not 1st year grad students who don't know what they are doing. The authors have decades of research and fabrication experience, and publications to back it up. Comments that insinuate it could be those kind of novice mistakes (other comments on HN/reddit, not yours) are frankly insulting and speaks to a profound arrogance in being unable to accept a new discovery.