Probing mixed valence states by nuclear spin-spin relaxation time measurements

Several elements in the periodic table exhibit an interesting and often overlooked feature: They skip certain valence states, which is discussed in the field of superconductivity to be in favor of fostering higher transition temperatures T_{c}. However, from the experimental point of view, it is oft...

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Bibliographic Details
Main Authors: Y. Ihara, M. Shimohashi, M. Kriener
Format: Article
Language:English
Published: American Physical Society 2025-03-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.7.L012080
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Summary:Several elements in the periodic table exhibit an interesting and often overlooked feature: They skip certain valence states, which is discussed in the field of superconductivity to be in favor of fostering higher transition temperatures T_{c}. However, from the experimental point of view, it is often deemed difficult to probe changes in the valence state. Here we demonstrate that the latter are accessible by the spin-spin relaxation rate 1/T_{2} in nuclear magnetic resonance. As target material, we chose the solid solution Ge_{1−x}In_{x}Te, where valence-skipping In induces superconductivity and changes its valence state as a function of x. We observe a strong enhancement in 1/T_{2}(x) and, most importantly, find that 1/T_{2} and T_{c} exhibit a strikingly similar x dependence. These results underline the importance of valence physics for the evolution of superconductivity in Ge_{1−x}In_{x}Te. A model based on a Ruderman-Kittel-Kasuya-Yosida type of interaction among the In nuclei is proposed which fully accounts for the experimental results.
ISSN:2643-1564