We have studied the nonlinear current-voltage characteristic of a two dimensional lattice Coulomb gas by Monte Carlo simulation. We present three different determinations of the power-law exponent $a(T)$ of the nonlinear current-voltage characteristic, $V

REFERENCES

[1]J.M.KosterlitzandD.J.Thouless,J.Phys.C5,L124(1972);6,1181(1973).

[2]V.L.Berezinskii,Zh.Eksp.Teor.Fiz.61,1144(1971)[Sov.Phys.JETP34,610(1972)].

[3]P.Minnhagen,Rev.Mod.Phys.59,1001(1987).

[4]A.M.Kadin,K.EpsteinandA.M.Goldman,Phys.Rev.B27,6691(1983).

[5]S.TeitelandC.Jayaprakash,Phys.Rev.B27,598(1983).

[6]J.Villain,J.dePhys.36,581(1975).

[7]tyshev,Pis’maZh.Eksp.Teor.Fiz.51,197-200(1990)

[JETPLett.51,224-227(1990)].

[8]A.K.Pradhan,S.J.Hazell,J.W.Hodby,C.Chen,Y.Hu,andB.M.Wanklyn,Phys.

Rev.B47,11374(1993).

[9]D.R.NelsonandJ.M.Kosterlitz,Phys.Rev.Lett.39,1201(1977).

[10]M.WallinandS.M.Girvin,Phys.Rev.B47,14642(1993).

[11]R.A.Hyman,M.Wallin,M.P.A.Fisher,S.M.Girvin,andA.P.Young,Phys.Rev.

B51,15304(1995).

[12]M.WallinandH.Weber,Phys.Rev.B51,6163(1995).

[13]J.-R.LeeandS.Teitel,Phys.Rev.B50,3149(1994).

[14]J.V.Jos´e,L.P.Kadano ,S.Kirkpatrick,andD.R.Nelson,Phys.Rev.B16,1217

(1977).

[15]J.-R.LeeandS.Teitel,Phys.Rev.Lett.64,1483(1990);Phys.Rev.B46,3247(1992).

[16]F.Reif,Fundamentalsofstatisticalandthermalphysics,McGraw-Hill(1965).

[17]V.Ambegoakar,B.I.Halperin,D.R.Nelson,andE.D.Siggia,Phys.Rev.Lett.40,