Observation of a transverse Meissner effect in CuxTiSe2 single crystals

We report on local magnetization measurements showing the presence of an unexpectedly strong transverse Meissner effect in the superconducting Cu_xTiSe₂ single crystals. We show that for tilted magnetic fields (H_a) vortices remain aligned with the a b planes up to field H_k∼H_p/sinθ_H (where θ_H is the angle between the applied field and the a b plane and H_p the first penetration field) and that for H_a>H_k , the field dependence of the vortex direction θ_B(H_a) can be well described assuming that vortices remain partially locked in the planes forming a staircase structure of average direction θ_B≠θ_H . These results indicate the existence of a strong modulation of the vortex core energy along the c axis but its origin remains unclear.