Substitution effects in RuO${}_2$ single crystals

Abstract

RuO${}_2$ has emerged as one of the leading candidates for investigating altermagnetism. Recent quantum oscillation and angle-resolved photoemission spectroscopy measurements found the absence of altermagnetism or antiferromagnetism in pure RuO${}_2$ crystals. The continuing debate over intrinsic magnetic order in RuO${}_2$ may reflect its proximity to an altermagnetic instability. In this work, we grow single crystals of Ru${}_{0.9}$V${}_{0.1}$O${}_2$ and investigate their structural, transport, and magnetic properties. X-ray photoelectron spectroscopy reveals an average V oxidation state near $+4$. The paramagnetic susceptibility remains nearly unchanged up to room temperature, with no evidence of magnetic ordering. Thus, the 10\% V-substitution in RuO${}_2$ does not induce altermagnetism. Electronic structure calculations for the V-substituted systems using two methods suggest that a higher level of V-substitution leads to a significant change in the density of states. These findings underscore the potential of nonmagnetic substitution in RuO${}_2$ as an attractive candidate for probing altermagnetic transitions and their experimental signatures.

11 pages, 7 figures, 4 tables