Transcript 幻灯片 1 - University of Alabama

Flux Dynamics of iron-based Superconductors
Bin Lv , X S Wu, H M Shao
National Lab of Solid State Microstructures, Nanjing University,
Nanijng210093, China
Introduction:
Vortex- glass
Microcosmic defects
Vortex lines
Hexangular Crystalline order
H
Defects center of material
In the presence of pinning, the long rang crystalline order of the Abrikosov lattice is destroyed. By taking into account
both pinning and collective effects of the vortex lines, at low T in a bulk system, the vortex lines should freeze into
vortex-glass phase. [1]
Theory and model
Previous function
[1]
 | T  Tg |
v ( z 1)
Tc>T>Tg
1D
By consider the effect of magnetic field, we introduce
another dimensionality-B.
New function
U 0 (T , B) v ( z 1)
 | 1 
|
Tc>T>Tg
kT
Vortex-glass
phase
Vortex-liquid
phase
Tg
Normal phase
T
Tc
2D
We have a more accurate description of vortex-glass.
U0(T,B)>U vortex-glass
U0(T,B)<U vortex-liquid
[2]
Use the experiential expression from experiment
1  T / Tc
U 0 (T , B)  kTc

( B / B0 )
We did different expansion in different T region, finally we get two theory curve, which can fit the original data quite well.
This is the first time that one could get the R-T curve at high T region from the glass theory.
Moreover, we found that in Ba0.6K0.4Fe2As2, the exponent v(z-1) decrease with the magnetic field
increase, not an irregular variety as observed in cuprate superconductors.
Reference
Acknowledgement
[1] R.H.Koch et al. PRL.63(1989) 1511
[2] A. Rydh et al. PRL.83(1999) 1850
This work has been supported by NNSFC (10774065, 10523001,
10974081) and NKPBRC (2006CB921802, 2010CB923404)