Tweed in Martensites: A Potential New Spin Glass

TL;DR

This paper proposes that the tweed precursors observed in shape-memory alloys above martensitic transitions are analogous to spin-glass phases, based on a two-dimensional model mapped onto a spin-glass Hamiltonian.

Contribution

It introduces a novel analogy between tweed precursors in martensitic alloys and spin-glass phases through a two-dimensional elastic model.

Findings

Tweed occurs hundreds of degrees above the martensitic transition.

The model maps onto a spin-glass Hamiltonian in a random field.

Tweed is intermediate between cubic and martensitic phases.

Abstract

We've been studying the ``tweed'' precursors above the martensitic transition in shape--memory alloys. These characteristic cross--hatched modulations occur for hundreds of degrees above the first--order shape--changing transition. Our two--dimensional model for this transition, in the limit of infinite elastic anisotropy, can be mapped onto a spin--glass Hamiltonian in a random field. We suggest that the tweed precursors are a direct analogy of the spin--glass phase. The tweed is intermediate between the high--temperature cubic phase and the low--temperature martensitic phase in the same way as the spin--glass phase can be intermediate between ferromagnet and antiferromagnet.