Observation of a transverse Meissner effect inCuxTiSe2single crystals

We report on local magnetization measurements showing the presence of an unexpectedly strong transverse Meissner effect in the superconducting ${\mathrm{Cu}}_{x}{\mathrm{TiSe}}_{2}$ single crystals. We show that for tilted magnetic fields $({H}_{a})$ vortices remain aligned with the $ab$ planes up to field ${H}_{k}\ensuremath{\sim}{H}_{p}/sin{\ensuremath{\theta}}_{H}$ (where ${\ensuremath{\theta}}_{H}$ is the angle between the applied field and the $ab$ plane and ${H}_{p}$ the first penetration field) and that for ${H}_{a}g{H}_{k}$, the field dependence of the vortex direction ${\ensuremath{\theta}}_{B}({H}_{a})$ can be well described assuming that vortices remain partially locked in the planes forming a staircase structure of average direction ${\ensuremath{\theta}}_{B}\ensuremath{\ne}{\ensuremath{\theta}}_{H}$. These results indicate the existence of a strong modulation of the vortex core energy along the $c$ axis but its origin remains unclear.