X-ray scattering studies of 2H-NbSe2, a superconductor and charge density wave material, under high external magnetic fields

Using x-ray scattering we have measured the response of the incommensurate charge-density wave (CDW) modulation in the quasi-low-dimensional material 2H-NbSe2 to applied magnetic fields at low temperatures. The application of a magnetic field, either perpendicular or parallel to the layers of a sing le crystal of 2H-NbSe2, caused no significant change to either the correlat ion length or the intensity of the CDW satellites for magnetic fields up to 10 T. These results suggest that the enhancement of the resistance observe d in low-dimensional CDW materials exposed to the applied magnetic field do es not result from an appreciable conversion of carriers from the normal st ate to the CDW state. In addition 2H-NbSe2 is a superconductor at low tempe ratures (T-c = 7.2 K), whilst still within the incommensurate CDW state. Th is material therefore affords an opportunity to study any interaction betwe en the CDW and superconducting condensates. High magnetic fields can suppre ss the superconducting stale yet no change in the incommensurate CDW satell ite correlation length or intensity was observed at high applied magnetic f ields. These results conflict with spectroscopic measurements, which sugges t a coupling between the superconducting gap excitations and the CDW.