Flux Lattice And Vortex Structure In 2h-Nbse2 In Inclined Fields

The structure's of the flux-line lattice and of individual vortices on the surface of a uniaxial anisotropic superconductor 2H-${\mathrm{NbSe}}_{2}$ are studied for arbitrary magnetic fields using the scanning tunneling microscope. The basis vectors show a distortion consistent with bulk anisotropic London theory, however, their angular orientation with respect to the tilt direction differs by about 30\ifmmode^\circ\else\textdegree\fi{} from that predicted. Various lattice-buckling instabilities are observed when the field is inclined more than 80\ifmmode^\circ\else\textdegree\fi{} away from the c axis. The star-shaped structure of the core distorts into a spiky comet shape as the field is tilted into the plane. If the field is along the surface (perpendicular to the c axis), evenly spaced parallel streaks reveal the subsurface vortex spacing.