Vortex dynamics in ferromagnetic / high Tc superconducting heterostructures

N. HABERKORN ; J. KIM; M. MIURA; B. MAIOROV; P. DOWDEN; L. CIVALE

Dallas

Congreso; APS March Meeting 2011; 2011

American Physical Society

In this work we explore the influence of the ferromagnetic landscape generated by magnetic phase separation in manganites on the vortex pinning of HTS/FM heterostructures. We have grown Gd2/3Ca1/3MnO3 (GCMO), Y2/3Ca1/3MnO3 (YCMO) and YBCO films, as well as GCMO/YBCO and YCMO/YBCO bilayers by Pulsed Laser Deposition. GCMO is a ferrimagnetic material with Curie temperature of  ~ 80 K and a compensation temperature of 15 K, whereas YCMO is ferromagnetic with Curie temperature ~ 80 K. In both materials the saturation magnetization is smaller than the value expected from ferrimagnetic and ferromagnetic order, suggesting phase separation with small ferromagnetic domains. The magnetic domain size as a function of temperature for the magnetic films was investigated using magnetic force microscopy (MFM). We will present a comparison of the vortex pinning and dynamics in the YBCO single layers and the GCMO/YBCO and YCMO/YBCO bilayers that allows us to identify the temperature and field regimes where magnetic pinning is effective.