Abstract
Vortex matter in layered high-[Formula: see text] superconductors, including iron-pnictides, undergo several thermodynamic phase transitions due to the complex interplay of pinning energy, thermal energy and elastic energy. Moreover, the presence of anisotropy makes their vortex physics even more intriguing. Here, we report a detailed vortex dynamics study, using dc magnetization measurements, in a triclinic iron-pnictide superconductor (Ca[Formula: see text]La[Formula: see text])[Formula: see text](Pt[Formula: see text]As[Formula: see text])(Fe[Formula: see text]As[Formula: see text])[Formula: see text], with a superconducting transition temperature, T[Formula: see text] [Formula: see text] 31 K. A second magnetization peak (SMP) feature is observed for magnetic field perpendicular (H[Formula: see text]c) and parallel (H[Formula: see text]ab) to the crystal plane. However, its fundamental origin is quite different in both directions. For H[Formula: see text]c, the SMP can be well explained using an elastic-to-plastic vortex creep crossover, using collective creep theory. In addition, a possible rhombic-to-square vortex lattice phase transition is also observed for fields in between the onset-field and peak-field related to the SMP. On the other hand, for H[Formula: see text]ab, a clear signature of an order-disorder vortex phase transition is observed in the isothermal M(H) measurements at T [Formula: see text] 6 K. The disordered phase exhibits the characteristics of entangled pinned vortex-liquid. We construct a comprehensive vortex phase diagram by displaying characteristic temperatures and magnetic fields for both crystal geometries in this unique superconducting compound. Our study sheds light on the intricate vortex dynamics and pinning in an iron-pnictide superconductor with triclinic symmetry.