Interface pinning in columnar defects

The interface pinning-depinning transition in a simple growth model for columnar random media is studied in connection with the absorbing state. In our model, the velocity v of the average surface height for various system sizes L follows a scaling relation v(L) similar to L(-betav/vx)g(t/L-zv) at the critical driving force F-c, where v(x), beta(v), and z(v) are the correlation length exponent, the velocity exponent, and the dynamic critical exponent, respectively. We find v(x) approximate to 1.0, z(v) approximate to 2.0, and beta(v) approximate to 1.0. The connection between the surface width exponents and the absorbing phase exponents are discussed.