Monte Carlo simulation of ion-beam channeling in YBa2Cu3O7

A Monte Carlo program (UPIC) for the simulation of ion channeling in crystals with complex structure is described. The program is applied to simulate the channeling of 1.5 MeV He+ and 1 MeV D+ near the [001] axis of YBa2Cu3O7 assuming strongly correlated atomic displacements along the [001] Cu-O rows in the superconducting state. The values for the abrupt change in the half-width of the channeling dip observed in experiments [R.P. Sharma et al., Phys. Rev. B 38 (1988) 9287] at the temperature of the superconducting transition, Tc, are reproduced in the simulations with correlation coefficients of 0.8-0.9. The increase in the minimum channeling yield at Tc found in measurements [T. Haga et al., Phys. Rev. B 41 (1990) 826] can be qualitatively explained by the increase in dechanneling rate due to correlations. ((orig.))