Emotional inhibitor
The Emotional inhibitor is a device fitted in all Cybus cybermen suits. It allows a human brain to be installed into a suit and exist without the brain suffering a "meltdown" of overwhelming emotions of what they had become.
Cancellation code
Mickey was able to hack into Cybus' mainframe and locate the code to which all of the cybermen's Emotional inhibitors operate on. He then texted the code to Rose's mobile phone, the Doctor grabbed her phone and interfaced it with the computer system. The code was shut down and the inhibitors turned off, unfortunately all the Cybermen had realised what they had become and died from the emotions they felt, Some even had their heads explode. The code was: 6879760.