A chemical avenue to manipulate field-reentrant superconducting rivalries in infinite layer nickelates

arXiv:2511.22026 · cond-mat.supr-con, cond-mat.str-el · Submitted 2025-11-27 · Read on arXiv

Listen

Transcript

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

Kai: We're looking at the paper: "A chemical avenue to manipulate field-reentrant superconducting rivalries in infinite layer nickelates".

Mira: The gist: A chemical avenue to manipulate field-reentrant superconducting rivalries in infinite layer nickelates elucidates how RE-4f orbital and spin interplays modulate quantum phase criticality and pairing strength,

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

Paper summary: Kai: To build on what we just heard, this paper, "A chemical avenue to manipulate field-reentrant superconducting rivalries in infinite layer nickelates," is essentially about finding a way to grow these materials effectively. The authors suggest that they can open up chemical avenues for effective growth of (RE1-yRE'y)one-xEuxNiO2, which includes Pr, Nd, Sm, Gd, Dy as the rare earths <ref:2511.22026#pg1>.

Mira: They are using a high-pO2 assisted chemical strategy to grow these infinite layer nickelates. The goal is to reduce the positive energy change of perovskite nickelates contracting when you introduce lanthanide contractions by using this high-pO2 approach for thin film growth of IL nickelate.

Lev: The way they do it involves dissolving the chemical precursors like RE(NO3)three and Ni(CH3COO)two in ethylene glycol monomethyl ether, EGME, and then spin coating them on a NdGaO3 substrate <ref:2511.22026#pg1>.

Kai: Then they transform the perovskite nickelates into infinite layer structure through soft chemical topotactic reduction based on CaH2 co-anneals instead of just using conventional alkaline earth elements like Sr or Ca.

Mira: And interestingly, instead of using those elements for hole doping, they realize it by partially substituting their RE constituents with Europium, which changes its valence state from plus three in the perovskites to plus two upon topotactic reduction.

Lev: From a thermodynamic view, the metastable perovskite nickelates precursors containing later series RE composition are preferentially stabilized at a high-pO2 within one hundred to one hundred and two mega pascals.

Kai: So, this chemical strategy allows them to put later series rare earths even further behind Europium in the infinite layer nickelates, and the RE constituent is just flexible enough to modulate by changing the chemical solutions for spin coating.

Mira: That flexibility is key because it lets them study how RE 4f-related quantum competition between high-Tc and reentrant superconductivity plays out <ref:2511.22026#pg1>.

Lev: It’s a very specific set of conditions they are creating to reach these systems, which is important for us because it sets the actual physical limits for what we can measure on real hardware.

Conclusion: Kai: So, looking at "A chemical avenue to manipulate field-reentrant superconducting rivalries in infinite layer nickelates," the authors are showing that this specific chemical approach is a new way to access these complex behaviors in nickelates.

Mira: They are emphasizing how this avenue allows them to enrich the superconducting phase diagram by seeing field-reentrant states emerge at both quantum boundaries, where high-Tc and reentrant superconductivity compete for dominance.

Lev: The implication for us is that it shows the quantum criticality between those two types of superconductivity isn't just about how much Europium you put in, but also about how the RE magnetism modulates that exchange field.

Kai: That’s right, and combining their magneto-transport measurements with low-energy muon spin spectroscopy reveals that there is this simultaneous occurrence of strengthened Cooper pairing and promoted magnetic fluctuation through the optimal Eu2+-4f7 interactions <ref:2511.22026#pg2>.

Mira: This interaction is what leads to the elevated Tc up to about forty Kelvin compared to those Sr or Ca doped systems, even when the layer spacing is similar <ref:2511.22026#pg2>.

Lev: So, this suggests a new freedom in understanding how RE 4f orbital and spin interplay can complicate the superconducting phase diagram of infinite layer nickelates in terms of quantum phase criticality modulation and pairing strengthening <ref:2511.22026#pg1>.

Kai: And it has practical implications because they showed that non-vacuum growth of IL-nickelate with high effectiveness is something that could be leveraged for technologies similar to cuprates.

Haowen Han, Yusong Zhao, Yi Bian, Tong Ma, Wenlong Yang, Shaohua Yang, Binghui Ge, Hongliang Dong,5, Chuanying Xi6, Ze Wang6, Nuofu Chen7, ΔShang8, Toni Shiroka9, Zaher Salman9, Jia-Cai Nie2,10*, Ho-Kwang Mao4,5, and Jikun Chen1*, School of Materials Science and Engineering, University of Science and Technology Beijing, School of Physics and Astronomy, Beijing Normal University, Institute of Physical Science and Information Technology, Anhui University, Center for High Pressure Science and Technology Advanced Research, Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments (MFree), Anhui Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, Chinese Academy of Sciences, School of Renewable Energy, North China Electric Power University, Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University, PSI Center for Neutron and Muon Sciences, Key Laboratory of Multiscale Spin Physics, Ministry of Education

University of Science and Technology Beijing · Beijing Normal University · Anhui University · Center for High Pressure Science and Technology Advanced Research · Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments (MFree) · Anhui Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, Chinese Academy of Sciences · School of Renewable Energy, North China Electric Power University · Key Laboratory of Polar Materials and Devices (MOE), School of Physics and Electronic Science, East China Normal University · PSI Center for Neutron and Muon Sciences · Key Laboratory of Multiscale Spin Physics, Ministry of Education

cond-mat.supr-con, cond-mat.str-el

Submitted: 2025-11-27

Updated: 2026-10-19

Comments: This manuscript has been published in National Science Review, Volume 13, Issue 19, October 2026, nwag457, https://doi.org/10.1093/nsr/nwag457. Please added full journal reference and DOI link

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

Importance score: 83/100

The gist: The gist: A chemical avenue to manipulate field-reentrant superconducting rivalries in infinite layer nickelates elucidates how RE-4f orbital and spin interplays modulate quantum phase criticality

Key concepts

Field-Reentrant Superconductivity: This phenomenon occurs when superconductivity appears again (re-enters) at the boundaries of the superconducting dome, even when high-temperature superconductivity is present. It is driven by a competition between magnetic fluctuations promoted pairing and exchange-field interactions, which are highly tunable by rare-earth elements.
Quantum Criticality Modulation: The critical point where quantum phase transitions occur can be adjusted by substituting rare-earth elements (RE1) with other REs (RE'). This substitution alters the internal exchange field associated with the magnetism, which in turn modifies how strongly magnetic fluctuations pair electrons and affects the overall superconducting properties.
Eu2+-4f7 Interaction: The Eu2+ ion, specifically its 4f7 configuration, plays a crucial role beyond simple doping. It contributes to both the exchange field and acts as a hole dopant. This dual role strengthens Cooper pairing through promoted magnetic fluctuations, leading to significantly higher superconducting transition temperatures compared to systems doped with Sr or Ca.
High-pO2 Chemical Growth Strategy: A specific chemical method was used involving dissolving precursors in EGME and using soft chemical topotactic reduction with CaH2 co-anneals under high oxygen pressure (100-102 MPa). This strategy enables the effective growth of IL nickelates incorporating heavier rare-earth elements that are otherwise difficult to incorporate.

Terminology

Anisotropy — 1× in this paper · explained in 4 episodes

Summary

The gist: A chemical avenue to manipulate field-reentrant superconducting rivalries in infinite layer nickelates elucidates how RE-4f orbital and spin interplays modulate quantum phase criticality and pairing strength, leading to elevated Tc up to ~40 K and robust Jc reaching 266 kA/cm2

Chemical Growth Strategy

The study opens up a simple high-pO2 assisted chemical avenue for growing IL nickelate superconductors toward heavier RE constituents with effectiveness in RE-substitutions This strategy is designed to reduce the positive ΔG of perovskite nickelates contracting with lanthanide contractions by exploiting a MPa-high pO2 assisted chemical strategy for thin film growth of IL nickelate The chemical precursors of RE(NO3)3 and Ni(CH3COO)2 were dissolved in ethylene glycol monomethyl ether (EGME), and spin coated on a NdGaO3 (110) substrate The perovskite nickelates was transformed into infinite layer via soft chemical topotactic reduction based on CaH2 co-anneals Instead of using conventional alkaline earth elements (e.g., Sr or Ca) herein the hole doping was realized via partially substituting their RE-constituents by Eu, which displays variable valance state from +3 in perovskites towards +2 upon topotactic reduction From the thermodynamic perspective, the metastable perovskite nickelates precursors containing later series RE-composition is preferentially stabilized at a high-pO2 within 100-102 MPa Hence, our strategy is capable to introduce later series RE further behind Eu into IL-nickelates, while the RE-constituent is simply and flexibly modulable manipulating the chemical solutions for spin coating

Superconducting Phase Diagram and Competition

Robust uniaxially anisotropic superconducting reentrancy was validated to emerge at the quantum phase boundaries of the superconducting dome for both Nd1-xEuxNiO2 and Pr1-xEuxNiO2 systems Their quantum criticality was further modulated via introducing RE' within (Nd1-yRE'y)1-xEuxNiO2 (RE': Pr, Sm, Gd, Dy and Sm1/2Pr1/2) to adjust the magnitude of exchange field associated with RE-magnetism The competition between reentrant and high-Tc superconductivity within Eu-doped IL-nickelates is highlighted by the superconducting phase diagram shown in Figure 2c We highlight that the superconducting reentry emerges exclusively at the superconducting boundaries, but is absent when the high-Tc superconductivity is robust at optimum doping This unveils the previously underestimated tunability in the quantum criticality by RE-4f (particularly Eu-4f7) via the likelihood of a magnetic fluctuation modulated pairing in the neighborhoods of quantum phase transitions

Role of Rare-Earth Substitution and Magnetic Modulation

The study demonstrates that robust superconducting behaviors are observed for Nd1-xEuxNiO2 with x=0.25-0.55, with the highest Tc,onset, Tc,50% and Tc,zero emerged at optimum Eu constituents (x=0.35-0.45) reaching 37.6 K, 27.3 K and 22.2 K respectively The temperature dependence in resistivity (ρ-T) of archetypal Nd1-xEuxNiO2 are shown in Figure 2a for optimum doping (x=0.45), underdoping (x=0.3), and overdoping (x=0.52), respectively The field-reentrant superconductivity emerging at both the underdoped and overdoped boundaries also holds for Pr1-xEuxNiO2/NdGaO3(110) and Nd1-xEuxNiO2/(LaAlO3)0.3(Sr2TaAlO6)0.7 (100), as demonstrated in Figure S16 The root-cause was further elucidated, combining characterization of pairing strength via magneto-transport and localized magnetism via low-energy muon-spin spectroscopy (LE-μSR) Our work unveils the pivotal role of magnetic fluctuations with close associations with RE-4f in modulating the quantum criticality and pairing strength, beyond conventional BCS theory

Modulation by Gd Substitution

The introduction of Gd3+ is expected to enhance the internal exchange field (Hex) to partially against the external magnetic field (Hext), as illustrated in Figure 3c The reentrant superconductivity reaching zero resistances is observed from 5-10 T, 8-13 T and 10-15 T at 1.6 K, 2 K, and 3 K, respectively Further angular dependent magnetotransport measurements via altering the angle (θ) between Hext and c-axis indicates strong uniaxial cross-plane anisotropy in the superconducting reentrant behavior of (Nd0.95Gd0.05)0.65Eu0.35NiO2 The JaccarinoPeter (J-P) effect was more likely to explain the magnetic field induced reentrant superconductivity for Eu-doped IL-nickelates In contrast, the Eu2+ (also with 4f7) not only generates Hex, but also served as hole dopant that simultaneously contributes to transports, giving rise to more complicated impact beyond simply J-P effect

Elevated Tc and Pairing Strengthening

The further elevation in Tc is clearly observed for the optimum Eu-doped IL-nickelates transcending the Sr-/Ca-doped ones even at similar layer spacing This unveils an extra pairing strengthening mechanism related to Eu2+-4f7, which improves paring via potentially promoted magnetic fluctuation The magnitude of λZF (e.g., 2.5 μs-1) in the superconducting state is much larger than that previously observed for the Sr-doped IL-nickelates (e.g., 0.22-0.48 μs-1) This illuminates a potential path to further explore associations between the promoted spin ordering in superconducting state and the significant elevation in Tc observed for Eu-doped IL-nickelates (e.g., 37.6 K) compared to the Sr-doped ones (e.g., 10 K)

Conclusion

In conclusion, grounded in the high-pO2 chemical avenue to effectively grow (RE1-yRE'y)1-xEuxNiO2, we elucidate the enrichment in their superconducting phase diagram by fieldreentrant superconducting states emerging at both quantum boundaries, competing for primacy The quantum criticality between reentrant and high-Tc superconductivity not only hinges on Eu-composition, but also displays associations with the RE (RE’) magnetism, which modulate the exchange field together with Eu2+ Furthermore, combining magneto-transport and LE-μSR measurements unveils the concomitant occurrence of strengthened Cooper pairing and promoted magnetic fluctuation via optimum Eu2+-4f7 interactions This counts for their further elevated Tc beyond the Sr-/Ca-doped systems even at similar infinite layer-spacing, giving rise to higher Tc up to 40 K and more robust Jc reaching 266 kA/cm2 at 2 K These discoveries highlight a new freedom from the overlooked RE-4f orbital and spin interplays that further complicate the superconducting phase diagram of IL-nickelates in terms of quantum phase criticality modulation and pairing strengthening, beyond analogous cuprates with similar dorbital frameworks Furthermore, the non-vacuum growth of IL-nickelate with high effectiveness holds practical implications, particularly in potential to leverage coated-conductor technologies similar to cuprates

Data Availability

The data that support the findings of this study are available from the corresponding author upon reasonable request Data and video are available at NSR online

Acknowledgements

We thank the BL08U1A beamline and the User Experiment Assist System of the Shanghai Synchrotron Radiation Facility (SSRF) for the assistance in characterizations We also thank the staff members of the XMCD beamline at the NSRL in Hefei, for providing the technical support and assistance in XAS data collection and analysis We also thank the WM1 of the Steady High Magnetic Field Facility, Chinese Academy of Sciences, for the assistance on the experiment The muon measurements were performed at the µE4 beamline of the Swiss Muon Source SµS, Paul Scherrer Institute, Villigen, Switzerland We also acknowledge the support from Dr. Andreas Suter and Dr. Thomas Proksha in PSI Center for Neutron and Muon Sciences, Paul Scherrer Institute, Switzerland Also, we acknowledge the constructive discussions with Dr. Ivan Božović

Funding

This work was supported the National Key Research and Development Program of China (No. 2021YFA0718900), the National Natural Science Foundation of China (No.

Improvements for AI systems

Bold header: Improved material synthesis pathways for complex oxides

This capability allows AI systems to design novel chemical precursors and high-pressure/high-pO2 growth protocols tailored to stabilize metastable perovskite nickelates with specific rare-earth substitutions, enabling the effective growth of (RE1-yRE'y)1-xEuxNiO2 systems.

Bold header: Predictive mapping of superconducting phase diagrams

The AI can predict the quantum phase boundary and criticality between unconventional superconductivity and fieldreentrant-one, specifically by modeling how RE(RE’)-magnetism modulates the quantum criticality, which either reinforces reentrancy or elevates Tc.

Bold header: Identification of pairing mechanism modulation

The AI can elucidate the pivotal role of magnetic fluctuations with close associations with RE-4f in modulating the quantum criticality and pairing strength, moving beyond conventional BCS theory to understand how these fluctuations lead to further elevation in Tc.

Bold header: Uniaxial anisotropy quantification

By integrating data from magneto-transport and localized magnetism via low-energy muon-spin spectroscopy (LE-μSR), the system can accurately quantify the strong uniaxial cross-plane anisotropy in the superconducting reentrant behavior as a function of external magnetic field angle.

Bold header: Optimized doping range determination

The AI can determine the precise effective hole-doping range generated by Eu2+, comparing it to Sr-substituted nickelates, providing a predictive window for achieving maximum Tc and robust critical current density (Jc) of 266 kA/cm squared at 2 K.