Thanks for your reply, my understanding is that what you have described is when a phonon mode has completely softened i.e. the energy of the phonon equals zero. However my question is when a phonon mode has reduced in energy but is not gone to zero.
If it makes it easier my specific case is...
I am interested in how phonon softening would lead to changes in a crystals elastic properties but I don't understand what actually is the consequence of this. What would be affected by a reduction in energy to phonons in a crystal?
My best guess would be a reduction in energy to phonons causes...
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...