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This paper reports a study of the nature and systematic variation of radiation damage to cuprate superconductors caused by several-hundred-MeV heavy ions. While irradiation of YBa2Cu307 q with 300-MeV Au + and 276-MeV Ag '+ ions produces columns of amorphous material along the ion trajectories, such defects are only created occasionally during irradiation with 236-MeV Cu' + and not induced with 182-MeV Si"+. A comparative study of the defect formation in Bi2Sr2Ca~Cu30 and oxygen-reduced and ozone-treated YBazCu307 z, shows that the degree of the radiation damage by the heavy ions depends on (a) the rate at which ions lose their energy in the target; (b) the crystallographic orientations with respect to the incident ion beam; (c) thermal conductivity and chemical state (oxygen concentration for YBa2Cu307 z) of the sample; and (d) the extent of preexisting defects in the crystal. A theoretical model based on ion-induced localized melting and the eA'ects of anisotropic thermal conductivity of these materials provides a basis for understanding the size and shape of the amorphous tracks. Measurements of the superconducting properties of Au +and Ag '+-irradiated YBa2Cu307 z thin films show a universal linear scaling between the fractional areal damage versus the superconducting transition temperature and the normal-state resistivity.

The issues of sign reversal of the Hall voltage and scaling between longitudinal (p xx ) and Hall (p xy ) resistivities are studied in Tl2Ba2Ca2Cu30io films in which the vortex dynamics is drastically changed by flux pinning at heavy-ion-irradiation-induced linear defects. While the sign anomaly diminishes with increasing defect concentration, the power law p xy~~p $ x , j3 = 1.85 ±0.1, holds even after irradiation. This result shows that the scaling is a universal feature of the mixed state in this system. The sign anomaly, on the other hand, is not consistent with a model that invokes pinning-induced backflow in the vortex core as the mechanism for this effect.PACS numbers: 74.60. Ge, 72.15.Gd, 74.62.Bf, Understanding the Hall coefficient in the mixed state of high temperature superconductors has become a rich area of research due to its two puzzling features which do not find satisfactory explanation in the confines of the classical hydrodynamic theories of vortex motion in charged superfluids. These are the following: (a) The Hall coefficient over a range of temperatures and magnetic fields below T c reverses its sign [1][2][3][4][5][6][7][8]. (b) A striking scaling behavior of the type p xy~~pxx ,where p xx and p xy are the longitudinal and Hall resistivities, respectively, and /J = 1.7, has been observed in the case of YBa 2 Cu3C>7 (YBCO) in a temperature range close to the onset of the Hall signal [8]. The sign anomaly has found various explanations such as (1) a two band model for the condensate in which the gap parameter for the minority band is much smaller [9], (2) effects of superconducting fluctuations [10], (3) a combination of Nernst-Ettinghausen and Seebeck effects that lead to a voltage opposite in sign to that of the Hall voltage due to the majority carriers [11], (4) phenomenological [6] and microscopic [12] modifications of the damping forces in order to establish a steady state vortex flow with a velocity component (v x ) antiparallel to the transport current, and finally (5) a theory [13] that includes pinning in the standard Bardeen-Stephen model [14] for flux flow and predicts a sign change with the increasing pinning strength. The scaling relation between p xy and p xx as reported by Luo et al. [8] in YBCO films has been argued to be a consequence of vortex-glass transition in a 3D vortex system with a weak, random disorder [15]. Recently, however, Vinokur and co-workers [16] have proposed that the relation p xy~~pxx , /? -2, is a general feature of any vortex state with disorder dominated dynamics. The experimental results of Samoilov on Bi 2 Sr 2 CaCu 2 O x [17] in the temperature and field range where the mixed state has a quasi-2D character [18,19] and is not likely to form a vortex-glass state [20] support this proposal.In this paper we address the issues of sign anomaly and scaling in the Tl 2 Ba 2 Ca2Cu30io (Tl-2223) system in which the vortex dynamics is drastically altered by heavy-ion-irradiation-induced linear defects. In the defect-free state, and the temperature range where d...