Influence of pressure on the transport, magnetic, and structural properties of superconducting Cr0.0009NbSe2 single crystal

Abstract

We investigate the superconducting critical current density (J_c), transition temperature (T_c), and flux pinning properties under hydrostatic pressure (P) for Cr_0.0009NbSe₂ 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.