A structural investigation of an electronic transition into a nematic phase of a quantum material at high magnetic field (0-100 T)*

Barium sodium osmate (Ba₂NaOsO₆) is a strongly spin-orbit coupled one 5d-electron system with a peculiar quantum-entangled long-range ordered (LRO) magnetic state. Furthermore, a field-induced phase transition into a novel nematic phase appears between paramagnetic (PM) and LRO state according to spectroscopic and specific-heat measurements. We present a set of high-precision single-crystal diffraction studies in persistent (~5T split-pair, 10T solenoid) and pulsed (30T solenoid) magnetic field complemented by Fiber-Bragg-Grating measurements of magnetostriction in non-destructive (60 T) and single-turn (100 T) coils to better understand nature of such a PM-to-nematic transition. An incisive discussion is presented considering structurally twinned nature of phases above and below this nematic transition.