Non local voltage effects in YBCO/LCMO-AF/LCMO-F trilayers

We consider nonlocal conductance effects in epitaxial trilayers made by ferromagnetic half-metal La2/3 Ca1/3 MnO3 and high Tc superconductor YBa2 Cu3 O7-? separated by an insulating barrier of antiferromagnetic La1/3 Ca2/3 MnO3 with variable thickness. The Hall transresistance as a function of the barrier thickness and the applied magnetic field is measured to investigate the interplay between tunneling and frictional drag effects in ferromagnet/ antiferromagnet/superconductor trilayers. The results show a subtle correlation between the tunneling and the drag to account for the observed decreasing of the transresistance as the barrier thickness and the magnetic field are varied. A phenomenological model addresses such features as an enhancement of the frictional drag when the process of tunneling gets suppressed.