Investigation of the Effects of Anisotropic and Symmetry-Breaking Strains on Hybridization and Quantum Phase Transitions in Strongly Correlated Quantum Materials.

Non-technical Abstract: The overarching scientific goals of this work are to explore and understand the effects of strain on a variety of quantum materials. Such materials present deep intellectual challenges as well as potential for future applications; developing new methods to interrogate and tune the properties of quantum materials is therefore of considerable importance. Strain refers to a forced change in the size and shape of a material. This changes the separation of atoms in the solid, which in turn affects the material properties. Such strain-tuning can yield key insights to the fundamental properties of quantum materials. It can also provide avenues to new applications. In terms of education and workforce development, a major societal impact associated with the research is the training of individuals in the science and art of crystal growth and characterization, areas that have been identified in several studies as being of particular national importance. The PI also collaborates widely, sharing materials synthesized as part of the work and enabling research at other institutions that would otherwise not be possible without access to such samples. The PI also participates in outreach activities for military veterans. Technical Abstract: The research examines several new directions and opportunities associated with investigating the effects of anisotropic and symmetry-breaking strains in strongly correlated quantum materials. In particular, this work studies materials that sit at the intersection of local moment and itinerant behavior, with the Kondo interaction providing the mechanism by which the local moments hybridize with a background of itinerant electronic states. The work has three main objectives: (1) To obtain direct measurements of the anisotropic Gruneissen ratios for representative materials via elastocaloric effect measurements; (2) To determine materials for which the phase diagram can be tuned most effectively by anisotropic strain; and (3) To examine the extent to which elastoresistance measurements can probe proximity to (and properties of) strain-tuned quantum phase transitions. The research involves crystal growth and characterization of the candidate materials, as well as performing detailed low-temperature strain-based measurements, principally of the adiabatic elastocaloric coefficients and the elastoresistivity tensor. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2505563 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Ian Fisher | Institution: Stanford University, STANFORD, CA | Award Amount: $604,621 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2505563 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2505563.html