Discovery of Compounds containing Frustrated Vanadium Nets with Emergent Electronic Phenomena

Colorado School Of Mines, Golden CO

Investigators

Abstract

Non-technical abstract: The emergence of new, complex quantum materials is critical for continued developments in quantum information, sensing, and computing. Recent discoveries of ternary compounds with frustrated vanadium sublattices, meaning magnetic spins cannot arrange in alternating directions (think putting the spins on the corners of a triangle), have revealed multiple exotic phenomena, including superconductivity, residing within a single material. Even more intriguingly, these phenomena are found to interact and compete. Understanding the implications of these interactions is challenging because only a few material examples are known. With this project, supported by the Solid State and Materials Chemistry program in NSF’s Division of Materials Research, Prof. Toberer and his research group employ strategies to discover new crystalline compounds that contain layers of magnetic vanadium atoms. First, active search algorithms are utilized to efficiently explore ternary vanadium chemical spaces through a combination of (i) first principles calculations of known and hypothetical compounds and (ii) bulk synthesis and structure determination. Second, the fundamental properties of new vanadium ternary compounds are determined through low temperature measurements and quantum mechanical calculations. Third, single crystals are grown of the most promising compounds for further low temperature measurements. Together, these tasks are expected to enable the next generation of quantum materials. Interwoven throughout these efforts are educational opportunities for undergraduate students and scientific engagement with the broader public. These include summer research opportunities, public lectures on the intersection of solid-state chemistry with mineralogy and gemology, and a week-long summer camp on solid-state chemistry for students from rural areas of Colorado. Technical abstract With support from the Solid State and Materials Chemistry program in NSF’s Division of Materials Research, Prof. Toberer and his research group seek to uncover new classes of vanadium polar intermetallics compounds where electronic correlations and topological band structures intersect on magnetically frustrated lattices. The inspiration for this research comes from recent discoveries within the KV3Sb5 and REV6Sn6 material classes; these compounds contain vanadium kagome sublattices that give rise to nontrivial topology, charge density waves, and superconductivity. The research begins with experimentally establishing ternary A-V-Z phase diagrams and associated novel compounds therein using bulk solid state chemistry approaches; these efforts leverage guidance from first principles calculations and physics-informed Bayesian optimization. For each new compound, the electronic structure and topology of each new compound is predicted using first principles methods for down-selection for single crystal growth using fluxes. Low temperature characterization of these single crystals reveals potential electronic instabilities arising from magnetic frustration; further characterization is facilitated through a commitment to sample sharing with the broader condensed matter community. The discovery and study of new quantum materials based on frustrated vanadium nets will ultimately enhance our understanding of the interaction between topology, charge density waves, and superconductivity. Interwoven throughout these activities are efforts to (i) build a new generation of STEM talent at the intersection of solid-state materials chemistry, condensed matter physics, and statistical decision making, (ii) broaden participation in STEM via targeted outreach, and (iii) engage the broader public in solid-state chemistry. 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.