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

arXiv:2512.11439 · cond-mat.supr-con, cond-mat.mtrl-sci · Submitted 2025-12-12 · Read on arXiv

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Introduction to the show: ident: Quantum Radio. Generated commentary on the latest quantum physics and condensed matter papers.

Kai: Today's paper: "Pressure-induced Lifshitz and quantum phase transitions in electron-doped cuprate superconductor".

Mira: The gist The study reports that applying pressure to Pr0.87LaCe0.13CuO4±δ (PLCCO) induces a Lifshitz transition at a critical pressure of 10 GPa,

Kai: First, who's behind it and why it matters.

Paper summary: Kai: Okay, so to summarize this piece on "Pressure-induced Lifshitz and quantum phase transitions in electron-doped cuprate superconductor," the main thrust is that applying pressure to PLCCO induces a Lifshitz transition at a critical pressure of about ten GPa <ref:2512.11439#pg2>.

Mira: They claim this transition shows up as a Fermi surface reconstruction, which then causes the superconductivity to fade out. The authors are looking at how external force can reorganize the electronic structure in these materials.

Lev: So the core idea is that we aren't just seeing a smooth change in properties; there’s a sharp reorganization happening at Pc because of carrier shifts.

Kai: Right, and what makes it specific to this study is their comprehensive measurements involving electrical resistance, Hall coefficient, and synchrotron X-ray diffraction at forty Kelvin <ref:2512.11439#pg3>. They found that the Hall resistance sign changes as pressure increases past that critical point.

Mira: The paper stresses that they performed XRD measurements at forty K across a wide range of pressures, from one point four GPa up to twenty point seven GPa, and crucially, no crystal structure phase transition was observed in this entire range.

Lev: That’s a big constraint for them; if the lattice is stable, the physics has to be purely electronic reorganization dictated by those pressure effects on the bands.

Kai: They used an effective two-band Hubbard model to explain this, showing that below ten GPa, electron and hole pockets coexist on the Fermi surface <ref:2512.11439#pg2>. Above ten GPa, these pockets merge into a single hole-dominated Fermi surface <ref:2512.11439#pg2>.

Mira: This merger is what they argue fundamentally alters the superconducting pairing strength J as pressure pushes it past Pc. It’s about how the carrier balance dictates the material's ability to superconduct under stress.

Lev: If you were trying to design a quantum device based on this, you’d have to build a system where you could precisely tune that carrier balance across that ten GPa threshold without inducing structural damage <ref:2512.11439#pg2>.

Kai: So, in short, the paper reports evidence for a pressure-induced Lifshitz transition in electron-doped cuprates, linking electronic structure changes directly to the suppression of superconductivity.

Mira: It matters because it adds a new dimension to how we understand tuning parameters like pressure and chemical doping in these complex superconductors.

Lev: It gives theorists a concrete mechanism—the FS reconstruction—to work with when they try to predict phase boundaries for these materials.

Conclusion: Kai: So looking at the whole piece, "Pressure-induced Lifshitz and quantum phase transitions in electron-doped cuprate superconductor," it really boils down to this: pressure acts like a switch that fundamentally rewires the electronic landscape of this material around ten GPa <ref:2512.11439#pg2>.

Mira: The authors, including Zhao, Cai, Liu, Zhang, Sun and others at the Center for High Pressure Science and Technology Advanced Research and the Institute of Physics Chinese Academy of Sciences and others listed in the paper, are pointing to a very specific mechanism: Fermi surface topology change.

Lev: It means that when you apply pressure to PLCCO single crystals at forty Kelvin, you aren't just compressing it; you are physically reshaping the pathways available for electrons to move and pair up <ref:2512.11439#pg3>.

Kai: The implication is that we need to look at the Fermi surface geometry, not just the lattice constant changes, when studying how external fields or pressure affect superconductivity in these compounds.

Mira: This work provides a strong link between carrier type dominance—electron versus hole pockets—and the superconducting state stability under pressure. It gives us a clearer picture of what happens to pairing strength J as the material moves from one carrier regime to another.

Lev: For experimentalists, it sets a clear target: if you want to study this transition, you need measurements sensitive enough to track that specific change in carrier contribution across that ten GPa pressure mark <ref:2512.11439#pg2>.

Kai: It’s about showing that the physics of superconductivity in these materials is deeply tied to the underlying electronic structure topology, not just bulk properties. That's what this paper contributes.

Center for High Pressure Science & Technology Advanced Research, Beijing 100193, China · Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China · Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments, Shanghai Advanced Research in Physical Sciences

cond-mat.supr-con, cond-mat.mtrl-sci

Submitted: 2025-12-12

Updated: 2026-10-08

Comments: 16 pages and 5 figures

Journal ref: PNAS 123(2026)e2622416123

License: http://creativecommons.org/licenses/by/4.0/

Importance score: 92/100

The gist: The gist The study reports that applying pressure to Pr0.87LaCe0.13CuO4±δ (PLCCO) induces a Lifshitz transition at a critical pressure of 10 GPa, which manifests as a Fermi surface reconstruction

Key concepts

Lifshitz Transition: This is a quantum phase transition where the shape of the electronic energy bands changes abruptly under pressure. In this material, it means the way electrons move through the crystal lattice fundamentally reorganizes itself at a critical pressure, leading to new electronic properties.
Fermi Surface Reconstruction: The Fermi surface is an imaginary boundary in momentum space that describes where electrons reside in the material. The paper found that pressure causes this boundary to change shape—reconstructing it—which significantly alters how electrons pair up to form the superconducting state.
Electron-Doped Cuprates: These are a class of high-temperature superconductors where extra electrons (doping) are added to the copper oxide lattice. The study focuses on how applying pressure affects these materials, specifically looking at how the electronic structure changes and impacts their superconducting behavior.

Terminology

Lifshitz transition — 21× in this paper · explained in 2 episodes
Phase Transitions — 4× in this paper · explained in 2 episodes
Core — 1× in this paper · explained in 2 episodes
Hubbard Model — 1× in this paper · explained in 3 episodes

Summary

The gist The study reports that applying pressure to Pr0.87LaCe0.13CuO4±δ (PLCCO) induces a Lifshitz transition at a critical pressure of 10 GPa, which manifests as a Fermi surface reconstruction and leads to the fading out of superconductivity > ref:2512.11439

Experimental Observations and Critical Pressure

The researchers conducted comprehensive high-pressure measurements on PLCCO single crystals using electrical resistance, Hall coefficient (RH), and synchrotron X-ray diffraction (XRD) at 40 K > ref:2512.11439. They observed that the ambient-pressure RH with a significantly negative value decreases with increasing pressure until it reaches zero at a critical pressure (Pc 10 GPa) > ref:2512.11439. Correspondingly, the superconducting transition temperature (Tc) exhibits a slight variation within this pressure range > ref:2512.11439. As pressure is further increased beyond Pc, RH changes its sign from negative to positive and then shows a slight increase, while Tc displays a continuous decrease > ref:2512.11439.

Structural Stability and Electronic Origin

XRD measurements at 40 K demonstrated that no crystal structure phase transition occurs across the Pc > ref:2512.11439. This finding suggests that all changes observed in the high-pressure transport measurements should be attributed to an electronic origin > ref:2512.11439. Specifically, the XRD patterns collected at 40 K showed that the sample crystallizes in the tetragonal T phase with space group I4/mmm for pressures ranging from 1.4 GPa to 20.7 GPa, encompassing the critical pressure for the sign change in Rxy (T) > ref:2512.11439. Furthermore, lattice parameters a and c showed a continuous reduction as pressure increased, demonstrating that no pressure-induced structural phase transition occurs in the investigated pressure range > ref:2512.11439.

Fermi Surface Reconstruction and Superconductivity

The observed behavior is associated with the pressure-induced reconstruction of the Fermi surface (FS), which is known as a Lifshitz transition > ref:2512.11439. This transition manifests by turning the superconductivity toward fading out > ref:2512.11439. The calculation further reinforces this Fermi surface reconstruction from electron-dominated to hole-dominated ones at around Pc > ref:2512.11439. Beyond Pc, Tc shows a monotonous decrease as pressure increases, while the positive RH exhibits a slight increase > ref:2512.11439. This monotonous decrease of Tc above Pc can be attributed to the reconstruction of the FS dominated by hole carriers, which significantly alters the superconductivity of materials > ref:2512.11439.

Theoretical Modeling and Carrier Balance

An effective two-band model, involving upper (UHB) and lower (LHB) Hubbard bands, was employed to calculate the evolution of band structure with pressure > ref:2512.11439. The model showed that R/t vanishes at Pc, signaling a Lifshitz transition with FS reconstruction > ref:2512.11439. Below Pc, electron- and hole-pockets coexist on the FS, and the essence of electron doping intrinsically enlarges the electron pocket which weakens pairing strength J > ref:2512.11439. Beyond Pc, the distinct electron- and hole pockets fully merge together to yield a single hole-dominated FS > ref:2512.11439.

Conclusion and Significance

The findings provide new evidence that highlights the strong correlation between the superconductivity and the Fermi surface topology in electron-doped cuprates > ref:2512.11439. This work is noted as being the first observation of pressure-induced Lifshitz transition in bulk electron-doped cuprate superconductors > ref:2512.11439. The results provide crucial experimental foundations and theoretical insights for a comprehensive understanding of both hole- and electron-doped cuprates > ref:2512.11439.

Improvements for AI systems

Better modeling of electronic structure evolution under pressure: The improved AI system can accurately predict how the distinct electron- and hole pockets fully merge together, yielding a single hole-dominated FS by utilizing the effective two-band model parameters, specifically modeling J/t as continuously decreasing with pressure, while R/t vanishes at Pc.
Detection of structural phase transitions: The system can distinguish between electronic effects and lattice changes by analyzing XRD data to determine if no crystal structure phase transition occurs in the investigated pressure range up to 20.7 GPa, contrasting this with the observation that a partial transition from the T phase to the T phase starts at 9.3 GPa at room temperature.
Correlation of transport and structural changes: The AI can establish a direct link between Fermi surface reconstruction and superconductivity by correlating experimental data, as suggested by the finding that the high-pressure behavior observed in PLCCO is associated with the pressure-induced reconstruction of the Fermi surface (FS) when no crystal structure phase transition occurs at the low temperature within the pressure range investigated.

Abstract

We report the first observations of a pressure-induced Lifshitz transition coupled with a quantum phase transition in electron-doped cuprate superconductor Pr0.87LaCe0.13CuO4 (PLCCO), by combining high-pressure electrical resistance, Hall coefficient and synchrotron X-ray diffraction (XRD) measurements at low temperatures. Our low-temperature Hall coefficient measurements reveal that the Hall coefficient decreases continuously and reaches zero at about 10 GPa (critical pressure of Pc1). Upon further compression beyond Pc1, Hall coefficient 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 (Tc) exhibits a monotonic suppression, vanishing completely at 17.6 GPa (critical pressure of Pc2), where the system enters a non-superconducting metallic state. Our low temperature XRD measurements unequivocally demonstrate the absence of any structural phase transition across Pc1 and Pc2. Therefore, the sign change in RH at Pc1 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 Pc2 contrasts sharply with known high-pressure behavior of hole-doped cuprates, uncovering a fundamental difference on how pressure tunes the ground states of electron- versus 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.