Critical Behavior of the Conductivity of Si:P at the Metal-Insulator Transition under Uniaxial Stress

We report new measurements of the electrical conductivity σ of the canonical three-dimensional metal-insulator system Si:P under uniaxial stress S. The zero-temperature extrapolation of σ(S,T→0)~|S-Sc|^μ shows an unprecedently sharp onset of finite conductivity at Sc with an exponent μ0ex0ex=0ex0ex1. The value of μ differs significantly from that of earlier stress-tuning results. Our data show dynamic σ(S,T) scaling on both metallic and insulating sides, viz. σ(S,T)0ex0ex=0ex0exσc(T) ̇ \.F^'(|S-Sc|/Tʸ) where σc(T) is the conductivity at the critical stress Sc. We find y0ex0ex=0ex0ex1/zν0ex0ex=0ex0ex0.34 where ν is the correlation-length exponent and z the dynamic critical exponent.