Velocity-force characteristics of a driven interface in a disordered medium - art. no. 184305

Using a dynamic functional renormalization group treatment of driven elasti c interfaces in a disordered medium, we investigate several aspects of the creep-type motion induced by external forces below the depinning threshold f(c). (i) We show that in the experimentally important regime of forces sli ghtly below f(c), the velocity obeys an Arrhenius-type law v similar to exp [- U(f)/T] with an effective energy barrier U(f) proportional to (f(c)-f) v anishing linearly when f approaches the threshold f(c). (ii) Thermal fluctu ations soften the pinning landscape at high temperatures. Determining the c orresponding velocity-force characteristics at low driving forces for inter nal dimensions d = 1,2 (strings and interfaces) we find a particular non-Ar rhenius-type creep v similar to exp[-(f(c)(T)/f)(mu)] involving the reduced threshold force f(c)(T) alone. For d = 3 we obtain a similar v-f character istic, which is, however, nonuniversal and depends explicitly on the micros copic cutoff.