High-quality RuO2 single crystals grown by self-sublimation: Transport, magnetism, and electrochemical properties

RuO2 is a widely studied transition-metal oxide in condensed-matter physics. Recent theoretical studies have proposed that RuO2 may host altermagnetism, but experimental verification requires high-quality single crystals. Here, we synthesize high-quality RuO2 single crystals by a self-sublimation method. Transport measurements reveal a remarkably high residual resistivity ratio of ∼1100, indicating high crystal quality and weak defect scattering. The resistivity from 2 to 300 K is well described within a Matthiessen-type framework, providing insights into the underlying scattering processes. Meanwhile, the temperature-dependent magnetic susceptibility exhibits predominantly paramagnetic behavior, with a field-induced magnetic moment of ∼10−5 μB at room temperature under an applied magnetic field of 0.1 T. Beyond its intrinsic physical properties, the RuO2 single crystals exhibit excellent electrochemical stability and enable the detection of biologically relevant hydrogen peroxide and essential ascorbic acid. These results establish high-quality RuO2 single crystals as a promising platform for investigating their intrinsic magnetic properties and potential altermagnetism, while also highlighting their potential for bioelectrochemical sensing applications.