Strain pseudospins with power-law interactions: Glassy textures of a cooled coupled-map lattice

被引:18
作者
Shenoy, S. R. [1 ,2 ]
Lookman, T. [3 ,4 ]
机构
[1] Univ Hyderabad, Sch Phys, Hyderabad 500046, Andhra Pradesh, India
[2] Abdus Salaam Int Ctr Theoret Phys, I-3414 Trieste, Italy
[3] Los Alamos Natl Lab, Div Theoret, Los Alamos, NM 87545 USA
[4] Univ Toronto, Dept Mat Sci & Engn, Toronto, ON M5S 3E, Canada
来源
PHYSICAL REVIEW B | 2008年 / 78卷 / 14期
关键词
D O I
10.1103/PhysRevB.78.144103
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
We consider a spin-1 model of strain pseudospins S(r)=0,+/- 1 that arise from a triple-well Landau free energy for a square/rectangle or "austenite-martensite" structural transformation of a two-dimensional lattice. The pseudospin model has elastic-compatibility-induced power-law anisotropic (PLA) interactions and no quenched disorder. The iteratively solved local mean-field equations for < S(r,t)> form a temperature-dependent PLA-coupled nonlinear-map lattice, where t is the iteration "time." On cooling at a constant rate, the excess entropy shows a weak roll-off near a temperature T=T-g and a sharper elbow at a lower T-*, just above a Kauzmann-type T-K where the excess entropy would have become negative. The crossover temperatures T-g,T-* decrease logarithmically with cooling rate and mark stability changes in spatiotemporal attractors of the cooled PLA-coupled map. Three phases in < S(r,t)> are found, with textures of the martensitic-variant domain walls as "inherent structures." There is a high-temperature (T>T-g) fine scale phase of feathery domain walls and an intermediate temperature (T-g>T>T-*) phase of mazelike domain walls, with both showing square-wave oscillations as predominantly period-two attractors but with minority-frequency subharmonic clusters. Finally, there is a low-temperature freezing (T-*>T) to a static fixed point or period-one attractor of coarse, irregular bidiagonal twins, as in a strain glass. A Haar-wavelet analysis is used to identify the local attractor dynamics. A central result is that dynamically heterogeneous and mobile low-strain droplets act as catalysts, and can form correlated chains or transient "catalytic corrals" to incubate an emerging local texture. The hotspot lifetime vanishes linearly in T-T-K, suggesting that T-K is a dynamic spinodal limit for generating the "austenitic" catalyst, the disappearance of which drives a trapping into one of many bidiagonal glassy states. The model has relevance to martensitic or complex-oxide textures, coupled-map lattices, and configurational-glass transitions.
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页数:17
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