Influence of pressure on the transport, magnetic, and structural properties of superconducting Cr 0.0009 NbSe 2 single crystal.

We investigate the superconducting critical current density ( J c ), transition temperature ( T c ), and flux pinning properties under hydrostatic pressure ( P ) for Cr 0.0009 NbSe 2 single crystal. The application of P enhances T c in both electrical resistivity (∼0.38 K GPa -1 : 0 ≤ P ≤ 2.5 GPa) and magnetization (∼0.98 K GPa -1 : 0 ≤ P ≤ 1 GPa) measurements, which leads to a monotonic increase in J c and flux pinning properties. The field-dependent J c at various temperatures under P is analyzed within the collecting pinning theory and it shows that δT c pinning is the crossover to δl pinning above the critical pressure ( P c ∼0.3 GPa). Our systematic analysis of the flux pinning mechanism indicates that both the density of pinning centers and pinning forces greatly increase with the application of P , which leads to an enhancement in the vortex state. Structural studies using synchrotron X-ray diffraction under pressure illustrate a stable hexagonal phase without any significant impurity phase and lattice parameter reduction with P shows highly anisotropic nature.