Pressure-induced Lifshitz and quantum phase transitions in electron-doped cuprate superconductors

We report observations of a pressure-induced Lifshitz transition coupled with a quantum phase transition in the electron-doped cuprate superconductor Pr 0.87 LaCe 0.13 CuO 4±δ , by combining high-pressure electrical resistance, Hall coefficient ( R H ), and synchrotron X-ray diffraction (XRD) measurements at low temperatures. Our low-temperature Hall coefficient ( R H ) measurements reveal that the R H decreases continuously and reaches zero at ~10 GPa (critical pressure of P c1 ). Upon further compression beyond P c1 , R H unexpectedly changes its sign from negative to positive, signaling a reconstruction of the Fermi surface from electron-dominated to hole-dominated topology. Concurrently, the superconducting transition temperature ( T c ) exhibits a monotonic suppression, vanishing completely at ~17.6 GPa (critical pressure of P c2 ), where the system enters a nonsuperconducting metallic state. Our low-temperature XRD measurements unequivocally demonstrate the absence of any structural phase transition across P c1 and P c2 . Therefore, the sign change in R H at P c1 is associated with a Lifshitz transition, which is never found in the compressed bulk electron- or hole-doped cuprate superconductors. Moreover, the quantum phase transition observed at P c2 contrasts sharply with known high-pressure behavior of hole-doped cuprates, uncovering a fundamental difference on how pressure tunes the ground states of electron- vs. hole-doped systems. These findings provide crucial insights into the different pressure responses on the interplay among Fermi surface topology, electronic correlations, and superconductivity between these two kinds of cuprate superconductors.