Pub Date : 2026-01-16DOI: 10.1038/s41535-026-00848-w
Kevin A. Smith, Yanhong Gu, Xianghan Xu, Heung-Sik Kim, Sang-Wook Cheong, Scott A. Crooker, Janice L. Musfeldt
Magnetoelectric multiferroics such as rare earth manganites host nonreciprocal behavior driven by low symmetry, spin-orbit coupling, and toroidal moments, although less has been done to explore whether lanthanides like Er3+ might extend functionality into the hard infrared for optical communications purposes. In this work, we reveal nonreciprocity in the f-manifold crystal field excitations of h-Lu0.9Er0.1MnO3. In addition to contrast in the highest fields, we demonstrate nonreciprocity at technologically-relevant energy scales--specifically in the E-, S-, and C-bands of the telecom wavelength range--and at low magnetic fields and room temperature. In fact, the low field behavior is consistent with possible altermagnetism. These findings advance the overall understanding of localized excitations in rare earth-containing systems and pave the way for entirely new types of telecom applications.
{"title":"Optical diode effect at telecom wavelengths in a polar magnet","authors":"Kevin A. Smith, Yanhong Gu, Xianghan Xu, Heung-Sik Kim, Sang-Wook Cheong, Scott A. Crooker, Janice L. Musfeldt","doi":"10.1038/s41535-026-00848-w","DOIUrl":"https://doi.org/10.1038/s41535-026-00848-w","url":null,"abstract":"Magnetoelectric multiferroics such as rare earth manganites host nonreciprocal behavior driven by low symmetry, spin-orbit coupling, and toroidal moments, although less has been done to explore whether lanthanides like Er3+ might extend functionality into the hard infrared for optical communications purposes. In this work, we reveal nonreciprocity in the f-manifold crystal field excitations of h-Lu0.9Er0.1MnO3. In addition to contrast in the highest fields, we demonstrate nonreciprocity at technologically-relevant energy scales--specifically in the E-, S-, and C-bands of the telecom wavelength range--and at low magnetic fields and room temperature. In fact, the low field behavior is consistent with possible altermagnetism. These findings advance the overall understanding of localized excitations in rare earth-containing systems and pave the way for entirely new types of telecom applications.","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"85 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145993481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-16DOI: 10.1038/s41535-026-00850-2
Daria I. Markina, Priyanka Mondal, Lukas Krelle, Sai Shradha, Mikhail M. Glazov, Regine von Klitzing, Kseniia Mosina, Zdenek Sofer, Bernhard Urbaszek
The van der Waals antiferromagnet CrSBr exhibits coupling of vibrational, electronic, and magnetic degrees of freedom, giving rise to distinctive quasi-particle interactions. We investigate these interactions across a wide temperature range using polarization-resolved Raman spectroscopy at various excitation energies, complemented by optical absorption and photoluminescence excitation (PLE) spectroscopy. Under 1.96 eV excitation, we observe pronounced changes in the ({A}_{g}^{1}), ({A}_{g}^{2}), and ({A}_{g}^{3}) Raman modes near the Néel temperature, coinciding with modifications in the oscillator strength of excitonic transitions and clear resonances in PLE. The distinct temperature evolution of Raman tensor elements and polarization anisotropy of Raman modes indicates that they couple to different excitonic and electronic states. The suppression of the excitonic states' oscillation strength above the Néel temperature could be related to the magnetic phase transition, thereby connecting these excitonic states and Raman modes to a specific spin alignment. We develop a simple model that describes how magnetic order impacts excitonic states and hence the intensity and polarization of the Raman scattering signal. These observations make CrSBr a versatile platform for probing quasi-particle interactions in low-dimensional magnets and provide insights for applications in quantum sensing and quantum communication.
{"title":"Interplay of vibrational, electronic, and magnetic states in CrSBr","authors":"Daria I. Markina, Priyanka Mondal, Lukas Krelle, Sai Shradha, Mikhail M. Glazov, Regine von Klitzing, Kseniia Mosina, Zdenek Sofer, Bernhard Urbaszek","doi":"10.1038/s41535-026-00850-2","DOIUrl":"https://doi.org/10.1038/s41535-026-00850-2","url":null,"abstract":"The van der Waals antiferromagnet CrSBr exhibits coupling of vibrational, electronic, and magnetic degrees of freedom, giving rise to distinctive quasi-particle interactions. We investigate these interactions across a wide temperature range using polarization-resolved Raman spectroscopy at various excitation energies, complemented by optical absorption and photoluminescence excitation (PLE) spectroscopy. Under 1.96 eV excitation, we observe pronounced changes in the ({A}_{g}^{1}), ({A}_{g}^{2}), and ({A}_{g}^{3}) Raman modes near the Néel temperature, coinciding with modifications in the oscillator strength of excitonic transitions and clear resonances in PLE. The distinct temperature evolution of Raman tensor elements and polarization anisotropy of Raman modes indicates that they couple to different excitonic and electronic states. The suppression of the excitonic states' oscillation strength above the Néel temperature could be related to the magnetic phase transition, thereby connecting these excitonic states and Raman modes to a specific spin alignment. We develop a simple model that describes how magnetic order impacts excitonic states and hence the intensity and polarization of the Raman scattering signal. These observations make CrSBr a versatile platform for probing quasi-particle interactions in low-dimensional magnets and provide insights for applications in quantum sensing and quantum communication.","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"38 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145993492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yttrium iron garnet (YIG) film, especially with perpendicular magnetic anisotropy (PMA), is a promising material for energy-efficient spintronic devices due to its extremely low damping constant. However, a poorly crystallized layer tends to form on the top surface of the YIG film during the annealing process, which severely hinders the interfacial spin transport. To overcome this limitation, we developed a surface treatment method using soft phosphoric acid. After the surface wet-etching treatment, both the spin mixing conductance and interfacial thermal conductance between the PMA-YIG film and post-deposited Pt layer can be increased by ~70% and ~100%, respectively. These PMA-YIG films with wet-etched surfaces hold promise for ultrahigh-density spintronic device applications.
{"title":"Surface wet-etched Y3Fe5O12 films with perpendicular magnetic anisotropy for ultrahigh density spintronic device applications","authors":"Shuyao Chen, Mingqian Yuan, Qixun Guo, Yunfei Xie, Dengfu Deng, Jiayi Zheng, Lintong Huang, Donghua Liu, Xuejun Yan, Ming-Hui Lu, Yan-Feng Chen, Tao Liu","doi":"10.1038/s41535-026-00847-x","DOIUrl":"https://doi.org/10.1038/s41535-026-00847-x","url":null,"abstract":"Yttrium iron garnet (YIG) film, especially with perpendicular magnetic anisotropy (PMA), is a promising material for energy-efficient spintronic devices due to its extremely low damping constant. However, a poorly crystallized layer tends to form on the top surface of the YIG film during the annealing process, which severely hinders the interfacial spin transport. To overcome this limitation, we developed a surface treatment method using soft phosphoric acid. After the surface wet-etching treatment, both the spin mixing conductance and interfacial thermal conductance between the PMA-YIG film and post-deposited Pt layer can be increased by ~70% and ~100%, respectively. These PMA-YIG films with wet-etched surfaces hold promise for ultrahigh-density spintronic device applications.","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"14 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-12DOI: 10.1038/s41535-025-00844-6
Linda Ye, Jorge I. Facio, Madhav Prasad Ghimire, Mun K. Chan, Jhih-Shih You, David C. Bell, Manuel Richter, Jeroen van den Brink, Joseph G. Checkelsky
We report a study of Shubnikov–de Haas oscillations in high-quality single crystals of ferromagnetic Weyl semimetal Co3Sn2S2. The Fermi surfaces resolved in our experiments are three-dimensional and reflect an underlying trigonal crystallographic symmetry. Combined with density functional calculations, we identify that multiple Fermi surfaces in the system—of both electron and hole nature—arise from the energy dispersion of the (spin-orbit gapped) mirror-protected nodal rings. We observe an evolution of the Fermi surfaces with in-plane magnetic fields, in contrast to field perpendicular to the kagome lattice planes, which has little effect. Viewed alongside the easy-axis anisotropy of the system, our observation reveals an evolution of the electronic structure of Co3Sn2S2—including the Weyl points—with the ferromagnetic moment orientation. Through the case study of Co3Sn2S2, our results provide concrete experimental evidence of an anisotropic interplay via spin-orbit coupling between the magnetic degrees of freedom and electronic band singularities, which has long been expected in semimetallic and metallic magnetic systems.
{"title":"Magnetization orientation-dependent Shubnikov-de Haas oscillations in ferromagnetic Weyl semimetal Co3Sn2S2","authors":"Linda Ye, Jorge I. Facio, Madhav Prasad Ghimire, Mun K. Chan, Jhih-Shih You, David C. Bell, Manuel Richter, Jeroen van den Brink, Joseph G. Checkelsky","doi":"10.1038/s41535-025-00844-6","DOIUrl":"https://doi.org/10.1038/s41535-025-00844-6","url":null,"abstract":"We report a study of Shubnikov–de Haas oscillations in high-quality single crystals of ferromagnetic Weyl semimetal Co3Sn2S2. The Fermi surfaces resolved in our experiments are three-dimensional and reflect an underlying trigonal crystallographic symmetry. Combined with density functional calculations, we identify that multiple Fermi surfaces in the system—of both electron and hole nature—arise from the energy dispersion of the (spin-orbit gapped) mirror-protected nodal rings. We observe an evolution of the Fermi surfaces with in-plane magnetic fields, in contrast to field perpendicular to the kagome lattice planes, which has little effect. Viewed alongside the easy-axis anisotropy of the system, our observation reveals an evolution of the electronic structure of Co3Sn2S2—including the Weyl points—with the ferromagnetic moment orientation. Through the case study of Co3Sn2S2, our results provide concrete experimental evidence of an anisotropic interplay via spin-orbit coupling between the magnetic degrees of freedom and electronic band singularities, which has long been expected in semimetallic and metallic magnetic systems.","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"83 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145956268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1038/s41535-025-00842-8
A. Jabed, F. Goto, B. Frimpong, D. Armanno, A. Longa, M. Michiardi, A. Damascelli, P. Hofmann, G. Jargot, H. Ibrahim, F. Légaré, N. Gauthier, S. Beaulieu, F. Boschini
The control of out-of-equilibrium electron dynamics in topological insulators is essential to unlock their potential in next-generation quantum technologies. However, the role of temperature on the renormalization of the electronic band structure and, consequently, on out-of-equilibrium electron scattering processes is still elusive. Here, using high-resolution time- and angle-resolved photoemission spectroscopy (TR-ARPES), we show that even a modest (~15 meV) renormalization of the conduction band of Bi 2 Te 3 can critically affect bulk and surface electron scattering processes. Supported by kinetic Monte Carlo simulations, we show that temperature-induced changes in the bulk band structure modulate the intervalley electron-phonon scattering rate, reshaping the out-of-equilibrium response and the long-lasting charge accumulation at the bottom of the conduction band. This work establishes temperature as an effective control knob for engineering scattering pathways in topological insulators.
{"title":"Control of intervalley scattering in Bi2Te3 via temperature-dependent band renormalization","authors":"A. Jabed, F. Goto, B. Frimpong, D. Armanno, A. Longa, M. Michiardi, A. Damascelli, P. Hofmann, G. Jargot, H. Ibrahim, F. Légaré, N. Gauthier, S. Beaulieu, F. Boschini","doi":"10.1038/s41535-025-00842-8","DOIUrl":"https://doi.org/10.1038/s41535-025-00842-8","url":null,"abstract":"The control of out-of-equilibrium electron dynamics in topological insulators is essential to unlock their potential in next-generation quantum technologies. However, the role of temperature on the renormalization of the electronic band structure and, consequently, on out-of-equilibrium electron scattering processes is still elusive. Here, using high-resolution time- and angle-resolved photoemission spectroscopy (TR-ARPES), we show that even a modest (~15 meV) renormalization of the conduction band of Bi <jats:sub>2</jats:sub> Te <jats:sub>3</jats:sub> can critically affect bulk and surface electron scattering processes. Supported by kinetic Monte Carlo simulations, we show that temperature-induced changes in the bulk band structure modulate the intervalley electron-phonon scattering rate, reshaping the out-of-equilibrium response and the long-lasting charge accumulation at the bottom of the conduction band. This work establishes temperature as an effective control knob for engineering scattering pathways in topological insulators.","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"264 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-09DOI: 10.1038/s41535-025-00845-5
Jeongkeun Song, Seoung-Hun Kang, Lucas Lindsay, Satoshi Okamoto, Yunkyu Park, Hu Miao, Jong Mok Ok, Ho Nyung Lee
Chiral transport in topological materials, arising from the interplay between topology and chirality, holds significant potential for energy-efficient spintronics and quantum information technologies through dissipationless, coherent charge flow. However, the emergence of chiral transport by tuning the electronic states of novel chiral materials is largely unexplored. Here, we report chiral transport driven by correlated Dirac fermions in SrNbO 3 epitaxial thin films, where strain-induced nonsymmorphic symmetry of oxygen octahedra tunes the material from metallic to Dirac states. Such symmetry-driven Dirac fermions feature a remarkable enhancement of electron mobility and magnetoresistance. Signatures of chiral transport induced by the chiral anomaly, including negative longitudinal magnetoresistance and twofold planar Hall oscillation, are observed in the Dirac semimetallic state, whereas they are absent in the metallic state of SrNbO 3 thin films. This work highlights a crucial role of symmetry engineering in generating chiral charge transport in oxide Dirac semimetals, opening an avenue to novel oxide-based topological and quantum devices.
{"title":"Symmetry-engineered chiral magnetotransport in the correlated oxide SrNbO3","authors":"Jeongkeun Song, Seoung-Hun Kang, Lucas Lindsay, Satoshi Okamoto, Yunkyu Park, Hu Miao, Jong Mok Ok, Ho Nyung Lee","doi":"10.1038/s41535-025-00845-5","DOIUrl":"https://doi.org/10.1038/s41535-025-00845-5","url":null,"abstract":"Chiral transport in topological materials, arising from the interplay between topology and chirality, holds significant potential for energy-efficient spintronics and quantum information technologies through dissipationless, coherent charge flow. However, the emergence of chiral transport by tuning the electronic states of novel chiral materials is largely unexplored. Here, we report chiral transport driven by correlated Dirac fermions in SrNbO <jats:sub>3</jats:sub> epitaxial thin films, where strain-induced nonsymmorphic symmetry of oxygen octahedra tunes the material from metallic to Dirac states. Such symmetry-driven Dirac fermions feature a remarkable enhancement of electron mobility and magnetoresistance. Signatures of chiral transport induced by the chiral anomaly, including negative longitudinal magnetoresistance and twofold planar Hall oscillation, are observed in the Dirac semimetallic state, whereas they are absent in the metallic state of SrNbO <jats:sub>3</jats:sub> thin films. This work highlights a crucial role of symmetry engineering in generating chiral charge transport in oxide Dirac semimetals, opening an avenue to novel oxide-based topological and quantum devices.","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"45 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Layered oxyselenides are of interest as promising mid- to high-temperature thermoelectric applications due to their tunable electrical properties and intrinsically low lattice thermal conductivity (κ). Understanding microscopic phonon mechanisms driving low-κ in these materials is essential for rational design. Here, we report a layer-differentiated phonon transport in Na2CoSe2O via solving the Wigner transport equation based on first-principles calculations, where CoSe6 and Na6O octahedra dominate acoustic and low-energy optical phonons, respectively, together inducing acoustic-optical bunching (a typical feature in homo-layered structures such as bilayer graphene and MoS2). In addition, Na6O generates high-energy flat optical phonons, in contrast to oxide-typical dispersive modes. This phonon dispersion feature, constrained by three-phonon scattering channels, necessitates interpretation via four-phonon processes, which simultaneously enhance wavelike coherent tunneling effects. Consequently, by considering anharmonic phonon renormalization, strong scattering of heat-carrying bunched phonons reduces κ by ~28%, with ~13% compensatory contribution from phonon coherence, yielding a low lattice thermal conductivity of 1.52 W m−1 K−1 at 300 K in Na2CoSe2O. This work provides new insights into the specific vibrational mechanisms, phonon bunching induced strong four-phonon scattering, highlights the critical role of distinct structural layers in governing thermal transport, and enriches the fundamental thermal transport mechanism in layered oxyselenides.
层状氧化硒化物由于其可调谐的电性能和固有的低晶格导热系数（κ）而被认为是有前途的中高温热电应用。了解这些材料中驱动低κ的微观声子机制对于合理设计至关重要。在这里，我们通过求解基于第一性原理计算的Wigner输运方程，报道了Na2CoSe2O中分层声子输运，其中CoSe6和na60八面体分别主导声子和低能光学声子，共同诱导声光聚束（双层石墨烯和MoS2等同质层结构的典型特征）。此外，与典型的氧化物色散模式相比，na60o产生高能量的平面光学声子。这种声子色散特征受到三声子散射通道的限制，需要通过四声子过程来解释，这同时增强了波状相干隧穿效应。因此，通过考虑非谐波声子重整化，携带热量的束状声子的强散射使κ降低了28%，声子相干性补偿了13%，从而在Na2CoSe2O中获得了300 K时1.52 W m−1 K−1的低晶格导热系数。本研究对声子聚集引起的强四声子散射的具体振动机制提供了新的见解，突出了不同结构层在控制热输运中的关键作用，丰富了层状硒化氧化物质的基本热输运机制。
{"title":"Phonon bunching induced strong four-phonon scattering for low lattice thermal conductivity in layered Na2CoSe2O","authors":"Bin Wei, Mengfan Chai, Chang Liu, Junyan Liu, Yongheng Li, Wenyu Zhang, Qing Wang, Erzhen Mu, Binbin Wang, Zhifang Zhou, Changpeng Lin, Xu Chen, Meihua Hu, Yunpeng Zheng, Yuan-Hua Lin","doi":"10.1038/s41535-025-00832-w","DOIUrl":"https://doi.org/10.1038/s41535-025-00832-w","url":null,"abstract":"Layered oxyselenides are of interest as promising mid- to high-temperature thermoelectric applications due to their tunable electrical properties and intrinsically low lattice thermal conductivity (κ). Understanding microscopic phonon mechanisms driving low-κ in these materials is essential for rational design. Here, we report a layer-differentiated phonon transport in Na2CoSe2O via solving the Wigner transport equation based on first-principles calculations, where CoSe6 and Na6O octahedra dominate acoustic and low-energy optical phonons, respectively, together inducing acoustic-optical bunching (a typical feature in homo-layered structures such as bilayer graphene and MoS2). In addition, Na6O generates high-energy flat optical phonons, in contrast to oxide-typical dispersive modes. This phonon dispersion feature, constrained by three-phonon scattering channels, necessitates interpretation via four-phonon processes, which simultaneously enhance wavelike coherent tunneling effects. Consequently, by considering anharmonic phonon renormalization, strong scattering of heat-carrying bunched phonons reduces κ by ~28%, with ~13% compensatory contribution from phonon coherence, yielding a low lattice thermal conductivity of 1.52 W m−1 K−1 at 300 K in Na2CoSe2O. This work provides new insights into the specific vibrational mechanisms, phonon bunching induced strong four-phonon scattering, highlights the critical role of distinct structural layers in governing thermal transport, and enriches the fundamental thermal transport mechanism in layered oxyselenides.","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"42 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145919919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-03DOI: 10.1038/s41535-025-00843-7
Ke Wang, Qijin Chen, Rufus Boyack, K. Levin
Pair-density-wave (PDW) states are a long-sought-after phase of quantum materials, with the potential to unravel the mysteries of high-Tc cuprates and other strongly correlated superconductors. Yet, surprisingly, a key signature of stable superconductivity, namely the positivity of the superfluid density, ns(T), has not yet been demonstrated. Here, we address this central issue by calculating ns(T) for a generic model two-dimensional PDW superconductor. We uncover a surprisingly large region of intrinsic instability, associated with negative ns(T), revealing that a significant portion of the parameter space thought to be physical cannot support a pure PDW order. In the remaining stable regime, we predict two striking and observable fingerprints: a small longitudinal superfluid response and an unusual temperature dependence for ns(T). These generally model-independent, as well as experimentally relevant findings suggest that the fragility of the superfluid density poses a significant problem for the formation of stable, finite temperature PDW superconductivity.
{"title":"Anomalous superfluid density in pair-density-wave superconductors","authors":"Ke Wang, Qijin Chen, Rufus Boyack, K. Levin","doi":"10.1038/s41535-025-00843-7","DOIUrl":"https://doi.org/10.1038/s41535-025-00843-7","url":null,"abstract":"Pair-density-wave (PDW) states are a long-sought-after phase of quantum materials, with the potential to unravel the mysteries of high-Tc cuprates and other strongly correlated superconductors. Yet, surprisingly, a key signature of stable superconductivity, namely the positivity of the superfluid density, ns(T), has not yet been demonstrated. Here, we address this central issue by calculating ns(T) for a generic model two-dimensional PDW superconductor. We uncover a surprisingly large region of intrinsic instability, associated with negative ns(T), revealing that a significant portion of the parameter space thought to be physical cannot support a pure PDW order. In the remaining stable regime, we predict two striking and observable fingerprints: a small longitudinal superfluid response and an unusual temperature dependence for ns(T). These generally model-independent, as well as experimentally relevant findings suggest that the fragility of the superfluid density poses a significant problem for the formation of stable, finite temperature PDW superconductivity.","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"255 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145894227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-30DOI: 10.1038/s41535-025-00840-w
Kinga Jasiewicz, Paweł Wójcik, Michał P. Nowak, Michał Zegrodnik
We study the interplay between altermagnetism and unconventional superconductivity for two-dimensional square- and triangular-lattice systems. Our approach is based on an effective single particle Hamiltonian which mimics the alternating spin splitting of the d-wave and i-wave altermagnetic state. By supplementing the model with intersite pairing term we characterize the principal features of the coexistent altermagnetic-superconducting state as well as the possibility of inducing the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. Our calculations show that the subtle interplay between the symmetries of the superconducting and altermagnetic order parameters as well as the shape/size of the Fermi surface lead to various types of anisotropic behaviors of the resultant non-zero momentum pairing, which has not been possible in the originally proposed FFLO state. Moreover, additional pairing symmetries appear leading to multi-component order parameter with singlet-triplet mixing. We discuss our result in the context of possible applications like, e.g., the superconducting diode.
{"title":"Interplay between altermagnetism and superconductivity in two dimensions: intertwined symmetries and singlet-triplet mixing","authors":"Kinga Jasiewicz, Paweł Wójcik, Michał P. Nowak, Michał Zegrodnik","doi":"10.1038/s41535-025-00840-w","DOIUrl":"https://doi.org/10.1038/s41535-025-00840-w","url":null,"abstract":"We study the interplay between altermagnetism and unconventional superconductivity for two-dimensional square- and triangular-lattice systems. Our approach is based on an effective single particle Hamiltonian which mimics the alternating spin splitting of the d-wave and i-wave altermagnetic state. By supplementing the model with intersite pairing term we characterize the principal features of the coexistent altermagnetic-superconducting state as well as the possibility of inducing the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. Our calculations show that the subtle interplay between the symmetries of the superconducting and altermagnetic order parameters as well as the shape/size of the Fermi surface lead to various types of anisotropic behaviors of the resultant non-zero momentum pairing, which has not been possible in the originally proposed FFLO state. Moreover, additional pairing symmetries appear leading to multi-component order parameter with singlet-triplet mixing. We discuss our result in the context of possible applications like, e.g., the superconducting diode.","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"29 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145894234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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