Anisotropic superconductivity in NbSe2 probed by magnetic penetration depth

International audienceNbSe2 shows coexistence of a charge density wave (TCDW similar to 32 K) with a superconducting state below T = 7.2 K. Recent ARPES measurements revealed different values of the superconducting gap on the main sheets of the Fermi surface. These results suggest a multigap superconductivity such as in MgB2. The temperature dependence of the magnetic penetration depth (;.(T)) down to T,11 6 has been measured on high quality single crystals in the Meissner state. A strong increase of the in-plane penetration depth is observed, signaling the presence of low lying excitations. Given the relative contributions of each Fermi surface sheet, these measurements indicate that a reduced gap is not necessarily only found on the small Se sheet as suggested by the ARPES measurements. These results are discussed in a framework of multigap superconductivity