Identification of novel compositions of ferromagnetic shape-memory alloys using composition spreads

Abstract

Exploration of new ferroic (ferroelectric, ferromagnetic or ferroelastic) materials continues to be a central theme in condensed matter physics and to drive advances in key areas of technology. Here, using thin-film composition spreads, we have mapped the functional phase diagram of the Ni-Mn-Ga system whose Heusler composition Ni(2)MnGa is a well known ferromagnetic shape-memory alloy. A characterization technique that allows detection of martensitic transitions by visual inspection was combined with quantitative magnetization mapping using scanning SQUID (superconducting quantum interference device) microscopy. We find that a large, previously unexplored region outside the Heusler composition contains reversible martensites that are also ferromagnetic. A clear relationship between magnetization and the martensitic transition temperature is observed, revealing a strong thermodynamical coupling between magnetism and martensitic instability across a large fraction of the phase diagram.

Compositional trends in Ni-Mn-Ga Heusler alloys: first-principles approach

“…We saw in previous studies that exploration of new materials can be significantly facilitated by the highthroughput techniques, which provide a complete picture of the compositional dependence [20]. We adopt the same approach in this work, but using the theoretical methodology.…”

Combinatorial search of superconductivity in Fe-B composition spreads

“…Previously, we have successfully implemented continuous composition spreads to discover new compositions of ferromagnetic a Electronic mail: kuijin@iphy.ac.cn shape memory alloys, morphotropic phase boundary piezoelectrics, giant magnetostrictive materials, etc. [8][9][10][11][12] Combinatorial libraries 13 and composition spreads have also been used in the past to demonstrate simultaneous synthesis of multiple superconducting compounds as well as to map compositional phase diagrams of known superconductors. [14][15][16] Fe and B targets were co-sputtered to generate mapping of a large fraction of the binary compositional phase space across 3 Si wafers with a 200 nm SiO 2 layer on top.…”

High-throughput screening of shape memory alloy thin-film spreads using nanoindentation

“…[16][17][18] We have used micromachined cantilever libraries, x-ray microdiffraction, and temperature-dependent electrical resistance measurements to screen our compositionspread samples for the presence of martensites. Here, we specifically report on the use of a nanoindenter to map the mechanical properties of thin-film composition spreads of the Ni-Mn-Al ternary system in order to identify the martensite composition region.…”