CONFINEMENT EFFECT IN MESOSCOPIC VORTEX MATTER AT LOW-FIELDS

N. R. CEJAS BOLECEK; M. I. DOLZ; C. J. VAN DER BEEK; H. PASTORIZA; A. KOLTON; Y. FASANO

Buenos Aires

Conferencia; Poster presentation en la conferencia Low Temperatures 27 (LT27)); 2014

IUPAP, Departamento de Física, UBA e Instituto de Física Conicet

We studied the effect of confinement in mesoscopic vortex matter nucleated in micron-sized Bi2Sr2CaCu2O8+δ disks  with  diameters  ranging  10  to  100  μm  and  2  μm height. We characterize the structural properties of mesoscopic vortex matter at low vortex densities  (less  than  1000  vortices  per  sample)  in  the  close‐to‐equilibrium  field‐cooling configuration with single‐vortex resolution by means of magnetic decoration experiments. In addition, we probe the configurational changes introduced  by  flux  penetration  in  zero‐field‐cooling experiments by means of differential magneto‐optical measurements.  The field and sample‐size  evolution  of  the  orientation  and  positional  orders  of  the  structure  indicates  the order   of   vortex   matter   worsen  on   decreasing  the   number   of   vortices.  The   vortex displacements  correlator  evolves  from  a  power‐law  to  a  linear  behaviour  on  increasing confinement.    These  effects  are  due  to  the  proliferation  of  topological  disorder  induced  by edge‐effects when decreasing the surface‐to‐volume ratio of the system.