Giant reduction of the phase transition temperature for beryllium doped VO2.

We propose a route to largely decrease the transition temperature for the insulator-metal transition of VO2 by doping with beryllium atoms. Our first-principles calculations show that the doped beryllium atoms can unprecedentedly decrease the phase transition temperature by 58 K per at% Be, which exceeds any doping attempts reported for VO2. Furthermore, it is found that the transition temperature of the Be-doped VO2 can be further lowered by applying external uniaxial pressure. A combination of Be-doping and external pressure realizes the occurrence of the phase transition at the desired room temperature. The nature of these findings is revealed to be essentially relevant to the strain-induced dimerization of V-V chains in the R-phased VO2.