Dataset: Dataset: Compensation doping of the qubit host Ba2CaWO6-δ

Authors: Abby Neill ¹, Lucas Pressley ¹, Tyrel McQueen ^1,2,3

Author affiliations:
¹:Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, United States
²:Institute for Quantum Matter and William H. Miller III Department of Physics and Astronomy,Johns Hopkins University, Baltimore, MD 21218, United States
³:Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, United States

Dataset associated with https://doi.org/10.1016/j.mtquan.2025.100029 which synthesized single crystals of nominal composition Ba2CaW1-xMxO6-δ (M = Zr4+, Ge4+) for x = 0-0.20. Electron paramagnetic resonance (EPR) and DC magnetic susceptibility measurements were used to understand the changes in spin-active defects as a function of substitution. We find that x = 0.01 (M = Zr4+) and x = 0.03 (M = Ge4+) are sufficient to quench the W5+ S = ½ EPR response (g = 2.00) within our limit of detection. Further substitution results in the appearance of a narrow S = ½ response (g = 1.98-2.00) that again fades away at higher compositions. The data support the conclusion that compensation doping is an effective strategy for modulation of single ion centers in Ba2CaWO6-δ and identify future steps that are needed to bring such complex materials to viability for QIS technologies, including proposal of an easily measured figure of merit for rapid materials iteration and optimization.