Scanning tunneling spectroscopy of the superconducting vortex lattice
DIPC Seminars
- Speaker
-
Isabel Guillamon (UAM, Madrid)
- When
-
2015/03/06
13:00 - Place
- Donostia International Physics Center (DIPC). Paseo Manuel de Lardizabal, 4, Donostia
- Add to calendar
- iCal
**Scanning tunneling spectroscopy of the superconducting vortex lattice**
Isabel Guillamón ****
_Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia
Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed
Matter Physics Center, Universidad Autónoma de Madrid_
_ _
Scanning tunneling spectroscopy allows imaging the superconducting vortex
lattice showing the behaviour of a single vortex up to the collective response
of the lattice. Moreover, experiments can be made from very low temperatures
up to the upper critical magnetic field providing microscopic insight over the
whole phase diagram.
Here I will present a recent work where we have imaged up to several thousands
of vortices one by one in a nanostructured superconductor and developed image
treatment algorithms that allow characterizing the collective response of the
lattice [1]. With these tools, we have studied the influence of quenched
random disorder on an ordered two dimensional (2D) vortex lattice.
In 2D systems, theory has proposed that random disorder destroys long-range
correlations driving a transition to a glassy state. In this talk, I will
discuss new insights into this issue obtained through the direct visualization
of the critical behaviour of a 2D superconducting vortex lattice formed in a
thin film with a smooth one-dimensional (1D) thickness modulation. By
nanofabricating the sample with 1D modulation, we produced controlled random
disorder. I will show how the hexagonal lattice starts floating over the
nanostructure, and how the floating lattice disorders due to the random
disorder. We observed a two-step order-disorder transition mediated by the
appearance of dislocations and disclinations and accompanied by an increase in
the local vortex density fluctuations. Through a detailed calculation of
correlation functions and critical exponents and by comparison with random
field theories, we find that the weak 1D correlations inhibit the effect of
random disorder and enhance the stability range of the ordered phase in a 2D
vortex lattice.
Work supported by Spanish MINECO, CIG Marie Curie grant, Axa Research Fund and
FBBVA.
Reference:
[1] I. Guillamon et al., Nature Physics 10, 851–856 (2014)
(host Nacho Pascual, nanoGUNE)