Electrical control of intervalley scattering in graphene via the charge   state of defects
  We study the intervalley scattering in defected graphene by low-temperature transport measurements. The scattering rate is strongly suppressed when defects are charged. This finding highlights "screening" of the short-range part of a potential by the long-range part. Experiments on calcium-adsorbed graphene confirm the role of a long-range Coulomb potential. This effect is applicable to other multivalley systems, provided that the charge state of a defect can be electrically tuned. Our result provides a means to electrically control valley relaxation and has important implications in valley dynamics in valleytronic materials. 
Baoming Yan and Qi Han and Zhenzhao Jia and Jingjing Niu and Tuocheng   Cai and Dapeng Yu and Xiaosong Wu
cond-mat.mes-hall