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arXiv · 2307.15312

NMR study of Ni50+xTi50-x Strain-Glass

Rui Li·Jacob Santiago·Daniel Salas·Ibrahim Karaman·Joseph H. Ross Jr
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Abstract

We studied Ni50+xTi50-x with compositions up to x = 2, performing 47Ti and 49Ti nuclear magnetic resonance (NMR) measurements from 4 K to 400 K. For large x in this system, a strain-glass appears in which frozen ferroelastic nano-domains replace the displacive martensite structural transition. Here we demonstrate that NMR can provide an extremely effective probe of the strain glass freezing process, with large changes in NMR line-shape due to the effects of random strains which become motionally narrowed at high temperatures. At the same time with high-resolution x-ray diffraction we confirm the lack of structural changes in x >= 1.2 samples, while we show that there is little change in the electronic behavior across the strain glass freezing temperature. NMR spin-lattice relaxation time (T1) measurements provide a further measure of the dynamics of the freezing process, and indicate a predominantly thermally activated behavior both above and below the strain-glass freezing temperature. We show that the strain glass results are consistent with a very small density of critically divergent domains undergoing a Vogel-Fulcher-type freezing process, coexisting with domains exhibiting faster dynamics and stronger pinning.

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Rui Li, Jacob Santiago, Daniel Salas, Ibrahim Karaman, Joseph H. Ross Jr. 2023-07-28. NMR study of Ni50+xTi50-x Strain-Glass. https://doi.org/10.1103/physrevb.107.144207

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