Highly effective superconducting vortex pinning in conformal crystals*

In the last few years, the search for an artificial pinning center (APC) distribution that pins a vortex lattice in a superconducting thin film over a wide magnetic field range has attracted a lot of attention. Recently, a conformal crystal obtained by conformally mapping a hexagonal lattice was proposed [1]. We compared the magneto-transport measurements of a conformal crystal and a randomly diluted APC distribution with a triangular reference lattice. We discovered for both APC distributions that the magneto-resistance is significantly reduced in a magnetic field interval between the first matching fields of the triangular reference lattice. Moreover, in this interval, the magneto-resistance of the conformal crystal APC distribution is below the noise floor indicating highly effective vortex pinning over a wide magnetic field range.\\[4pt] [1] D. Ray et al., Phys. Rev. Lett. 110, 267001 (2013)