Metallisation of the Mott Insulator Ca${}_2$RuO${}_4$ using Electric Double-Layer Gating

To verify whether the Mott insulator Ca2RuO4 can be switched by applying electric-field alone, regardless of current flow, we employ metallisation using electric double-layer gating (EDLG). The resistance change due to EDLG occurs only when positive gate-voltage above +3 V is applied. The amplitude of the reduction, reaching ~97% of the initial value, is difficult to interpret as surface metallisation and is likely related to structural change in bulk.