Crystal growth and anisotropic superconducting properties of Sr2VFeAsO3

Abstract: We have succeeded in growing single crystals of the Sr2VFeAsO3 superconductor, which are large enough to experimentally elucidate the anisotropic physical properties in this system. Using the obtained single crystals, superconducting properties under magnetic fields parallel to the c-axis (H//c) and ab-plane (H//ab) have been evaluated. It is found that the irreversibility field/temperature, below which the superconducting critical current density (J c) becomes finite, is highly anisotropic in Sr2VFeAsO3: the irreversible region is reduced by approximately half for the case of H//c as compared with H//ab. The suppression of the irreversibility temperature by H//c is found to be the largest among the Fe-based superconductors and comparable to the highly anisotropic Bi–Cu-based high-T c superconductors. The rapid decrease of J c with increasing H//c and T in the irreversible region is also observed. Therefore, there are pronounced fluctuations in the mixed state of Sr2VFeAsO3, suggesting that the vortices are in the pancake state as discussed in the Bi–Cu-based high-T c superconductors. [Copyright &y& Elsevier]