Observation of a strongly nested Fermi surface in the shape-memory alloy Ni[0.62]Al[0.38]

TL;DR

This study reveals a strongly nested Fermi surface in Ni[0.62]Al[0.38], linking electronic structure to martensitic precursor phenomena through Compton scattering analysis.

Contribution

It provides the first direct experimental evidence of Fermi surface nesting in this shape-memory alloy, connecting electronic topology to martensitic transformations.

Findings

Fermi surface exhibits strong nesting with a specific wavevector.

Nesting correlates with phonon softening and diffuse streaking.

Enhanced electron-lattice coupling is driven by Fermi surface topology.

Abstract

The Fermi surface topology of the shape-memory alloy Ni[0.62]Al[0.38] has been determined using Compton scattering. A large area of this Fermi surface can be made to nest with other areas by translation through a vector of ~ 0.18 [1,1,0] (2pi/a), which correponds to the wavevector associated with martensitic precursor phenomena such as phonon softening and diffuse streaking in electron diffraction patterns. This observation is compelling evidence that these phenomena are driven by the enhanced electron-lattice coupling due to the Fermi surface nesting.