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Optical decoherence in Er$^{3+}$-doped CeO$_2$ spin qubit platforms
Authors:
Vrindaa Somjit,
Ignas Masiulionis,
Gregory D. Grant,
Weiguo Jing,
Matteo Giantomassi,
Supratik Guha,
Gian-Marco Rignanese,
F. Joseph Heremans,
Jiefei Zhang,
Giulia Galli
Abstract:
Erbium ions (Er$^{3+}$) in cerium dioxide (CeO$_2$) represent a promising spin-photon interface for quantum communication, but the mechanisms limiting their optical coherence remain poorly understood. Using periodic hybrid density functional theory calculations with finite-size corrections, we identify Ce$^{3+}$ polarons and their complexes with oxygen vacancies and Er$^{3+}$ dopants as likely sou…
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Erbium ions (Er$^{3+}$) in cerium dioxide (CeO$_2$) represent a promising spin-photon interface for quantum communication, but the mechanisms limiting their optical coherence remain poorly understood. Using periodic hybrid density functional theory calculations with finite-size corrections, we identify Ce$^{3+}$ polarons and their complexes with oxygen vacancies and Er$^{3+}$ dopants as likely sources of optical decoherence. These defects exhibit finite photoionization cross-sections at 0.8 eV, coinciding with both the laser excitation energy used experimentally and the emission energy of Er$^{3+}$. This resonance enables photoionization of the polarons and photoluminescence quenching of Er$^{3+}$, leading to the broadening of optical linewidths, shortening of excited-state lifetimes, and introduction of charge noise. Our concentration-dependent photocurrent measurements in Er$^{3+}$-doped CeO$_2$ films under 0.8 eV illumination validate the predicted decoherence pathway. Our combined computational and experimental results identify a concrete defect-engineering target for improving the Er$^{3+}$-doped CeO$_2$ platform, and point to a decoherence mechanism likely relevant to other Er$^{3+}$-doped multivalent-oxide quantum platforms.
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Submitted 18 August, 2026;
originally announced August 2026.
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Termination-Dependent Surface States and Magnetic Fingerprints of Chiral Helimagnet Cr1/3TaS2
Authors:
Bo Liang,
Xue Li,
Congcong Le,
Zirui Wu,
Wenpei Zhu,
Neng Cai,
Yong-Chang Lau,
Xianxin Wu,
Jiayu Liu,
Zhanfeng Liu,
Hongen Zhu,
Tongrui Li,
Zhicheng Jiang,
Yu Huang,
Wenchuan Jing,
Xun Ma,
Qi Jiang,
Hang Li,
Zhihao Cai,
Xuezhi Chen,
Gexing Qu,
Yiwei Cheng,
Bing-Jie Chen,
Zhengtai Liu,
Dawei Shen
, et al. (14 additional authors not shown)
Abstract:
Chiral helimagnets based on intercalated transition-metal dichalcogenides, characterized by nano-scale spin ordering, provide a powerful route to engineer chiral spin textures (e.g. the topologically protected magnetic solitons) and emergent electronic functionality at reduced dimensions, where surface and interface states often dominate device operation. However, despite growing interest, direct…
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Chiral helimagnets based on intercalated transition-metal dichalcogenides, characterized by nano-scale spin ordering, provide a powerful route to engineer chiral spin textures (e.g. the topologically protected magnetic solitons) and emergent electronic functionality at reduced dimensions, where surface and interface states often dominate device operation. However, despite growing interest, direct experimental studies of termination-dependent surface electronic structures and their temperature-driven magnetic evolution remain largely unexplored, hindering a microscopic understanding of the electronic states that is crucial for the development of low-dimensional spintronic devices. Here, for the first time, taking Cr1/3TaS2 as a representative example, we systematically investigate the termination-dependent surface electronic states of the chiral helimagnets and uncover their distinct temperature evolution across the magnetic transition (TC~142K) by combining high-resolution ARPES with a micro-focused beam and surface-state-resolved first-principles calculations. The TaS2-terminated surface hosts folded monolayer-like TaS2 bands under the $\sqrt3\times\sqrt3$ superlattice potential and a shallow triangular electron pocket at the superlattice $\bar K$ point arising from Cr-Ta orbital hybridization. In contrast, the Cr-terminated surface exhibits reconstructed hole pockets with pronounced magnetic band splitting. This splitting disappears above TC and closely follows the chiral helimagnetic order parameter, providing a direct spectroscopic fingerprint of chiral helimagnetic order. In addition, multiple ultranarrow Cr-d-derived surface flat bands are resolved. These findings establish Cr1/3TaS2 as a model system in which surface electronic states are strongly coupled to chiral magnetism, opening new opportunities for chiral spintronic and valleytronic micro/nanodevices.
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Submitted 23 May, 2026;
originally announced May 2026.
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Altermagnetism, ARPES, symmetry, non-relativistic band splitting
Authors:
Jiayu Liu,
Xun Ma,
Xinnuo Zhang,
Wenchuan Jing,
Zhengtai Liu,
Dawei Shen
Abstract:
Altermagnetism arises from composite real-space and spin-space symmetries, combining zero net magnetization with pronounced momentum-dependent spin splitting. This review highlights the pivotal role of angle-resolved photoemission spectroscopy (ARPES), along with its spin-resolved (SARPES) and circular-dichroism (CD-ARPES) variants, in directly visualizing nonrelativistic band splitting and spin t…
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Altermagnetism arises from composite real-space and spin-space symmetries, combining zero net magnetization with pronounced momentum-dependent spin splitting. This review highlights the pivotal role of angle-resolved photoemission spectroscopy (ARPES), along with its spin-resolved (SARPES) and circular-dichroism (CD-ARPES) variants, in directly visualizing nonrelativistic band splitting and spin textures in altermagnets. Within the spin-group framework, we distinguish ferromagnetic, antiferromagnetic, and altermagnetic orders and elucidate the symmetry origin of spin polarization. We then systematically review representative systems: the debated d-wave prototype RuO2, layered d-wave altermagnets KV2Se2O and Rb1-delta V2Te2O, and a series of g-wave compounds including MnTe (domain-tunable) and CrSb (topological), together with the noncoplanar antiferromagnet MnTe2 and other emerging candidate platforms. Overall, ARPES has become a key probe for resolving symmetry-driven spin splitting. Future advances in micro/nano-beam and in-situ spectroscopies, combined with strain and domain engineering, heterostructure design, and exploration of broader unconventional magnetic states, are expected to drive the joint evolution of altermagnetism and photoemission spectroscopy, paving the way for spintronic and correlated quantum research.
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Submitted 13 February, 2026;
originally announced February 2026.
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Direct Observation of Unidirectional Density Wave and Band splitting in a Single-Domain Trilayer Nickelate Pr$_4$Ni$_3$O$_{10}$
Authors:
Zhicheng Jiang,
Enkang Zhang,
Yuxin Wang,
Zhengtai Liu,
Jishan Liu,
Runfeng Zhang,
Xinnuo Zhang,
Wenchuan Jing,
Yu Huang,
Qi Jiang,
Mao Ye,
Kun Jiang,
Jun Zhao,
Dawei Shen,
Donglai Feng
Abstract:
Unraveling the interplay between density-wave (DW) instabilities and multi-orbital physics is critical for understanding superconductivity in Ruddlesden-Popper nickelates, yet intrinsic electronic features have been persistently obscured by material inhomogeneity and thus the multi-domain averaging effect. Here, we employ micro-focused angle-resolved photoemission spectroscopy ($μ$-ARPES) on singl…
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Unraveling the interplay between density-wave (DW) instabilities and multi-orbital physics is critical for understanding superconductivity in Ruddlesden-Popper nickelates, yet intrinsic electronic features have been persistently obscured by material inhomogeneity and thus the multi-domain averaging effect. Here, we employ micro-focused angle-resolved photoemission spectroscopy ($μ$-ARPES) on single-domain Pr$_4$Ni$_3$O$_{10}$ to disentangle the complex hierarchy of intrinsic and back-folded bands, explicitly identifying the electronic states driving the DW phase transition. We provide decisive spectroscopic evidence that the low-energy reconstruction is governed by inter-orbital nesting between the $α$ and $β$ bands. Specifically, we resolve a orbital-dependent gap of $\sim44$ meV on the $α$ pocket, a value quantitatively consistent with prior measurements, unifying previously conflicting experimental reports regarding the locus and magnitude of the DW gap. Furthermore, we reveal strong orbital-selective mass renormalization in the $d_{z^2}$ states and successfully resolve the long-sought intrinsic trilayer $β$-band splitting, establishing a critical lower bound for the outer-layer hopping. These results define a coherent microscopic fingerprint for the trilayer nickelates, identifying the specific nesting channels and correlation effects that underpin the phase diagram.
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Submitted 2 February, 2026;
originally announced February 2026.
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Many-body electronic structure in pyrochlore superconductor CsBi2 and spin liquid Pr2Ir2O7
Authors:
Wei Song,
Guowei Liu,
Hanbin Deng,
Tianyu Yang,
Yongkai Li,
Xiao-Yu Yan,
Ruoxing Liao,
Qianming Wang,
Jiayu Xu,
Chao Yan,
Yuanyuan Zhao,
Hailang Qin,
Da Wang,
Wenchuan Jing,
Dawei Shen,
Kosuke Nakayama,
Takafumi Sato,
Chandan Setty,
Desheng Wu,
Boqing Song,
Tianping Ying,
Zhaoming Tian,
Akito Sakai,
Satoru Nakatsuji,
Harish Kumar
, et al. (4 additional authors not shown)
Abstract:
The pyrochlore lattice materials can exhibit geometrical frustration, while the related many-body electronic states remain elusive. In this work, we performed scanning tunneling microscopy measurements on the pyrochlore superconductor CsBi2 and spin liquid Pr2Ir2O7 at 0.3 K. For the first time, we obtained atomically resolved images of their (111) surfaces, revealing a hexagonal lattice or a kagom…
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The pyrochlore lattice materials can exhibit geometrical frustration, while the related many-body electronic states remain elusive. In this work, we performed scanning tunneling microscopy measurements on the pyrochlore superconductor CsBi2 and spin liquid Pr2Ir2O7 at 0.3 K. For the first time, we obtained atomically resolved images of their (111) surfaces, revealing a hexagonal lattice or a kagome lattice. Tunneling spectroscopy in CsBi2 reveals a nearly fully opened superconductivity gap. The ratio of 2Δ/kBTC = 4.7 suggests relatively strong coupling superconductivity, as compared with that in kagome superconductors AV3Sb5 (A = K, Rb, Cs). In contrast to the previous study categorizing CsBi2 as a type-I superconductor, the applied magnetic field induces a hexagonal vortex lattice in which each vortex core exhibits an intriguing three-fold symmetry state. In Pr2Ir2O7, we observed a spatially homogeneous Kondo-lattice resonance, which is compared with that in the kagome Kondo-lattice material CsCr6Sb6. We further discover that the Kondo resonance exhibits a spatial modulation with three-fold symmetry, and the applied magnetic field induces a Zeeman splitting of the Kondo resonance with intriguing atomic site dependence. We discuss the relations of these many-body electronic phenomena with the pyrochlore lattice geometry and its charge or spin frustration. Our systematic observations offer atomic-scale insights into the many-body electronic structures of the geometrically frustrated pyrochlore superconductors and spin liquids.
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Submitted 22 November, 2025;
originally announced November 2025.
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Large band-splitting in $g$-wave type altermagnet CrSb
Authors:
Jianyang Ding,
Zhicheng Jiang,
Xiuhua Chen,
Zicheng Tao,
Zhengtai Liu,
Tongrui Li,
Jishan Liu,
Jianping Sun,
Jinguang Cheng,
Jiayu Liu,
Yichen Yang,
Runfeng Zhang,
Liwei Deng,
Wenchuan Jing,
Yu Huang,
Yuming Shi,
Mao Ye,
Shan Qiao,
Yilin Wang,
Yanfeng Guo,
Donglai Feng,
Dawei Shen
Abstract:
Altermagnetism (AM), a newly discovered magnetic state, ingeniously integrates the properties of ferromagnetism and antiferromagnetism, representing a significant breakthrough in the field of magnetic materials. Despite experimental verification of some typical AM materials, such as MnTe and MnTe$_2$, the pursuit of AM materials that feature larger spin splitting and higher transition temperature…
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Altermagnetism (AM), a newly discovered magnetic state, ingeniously integrates the properties of ferromagnetism and antiferromagnetism, representing a significant breakthrough in the field of magnetic materials. Despite experimental verification of some typical AM materials, such as MnTe and MnTe$_2$, the pursuit of AM materials that feature larger spin splitting and higher transition temperature is still essential. Here, our research focuses on CrSb, which possesses N{é}el temperature of up to 700K and giant spin splitting near the Fermi level ($E_F$). Utilizing high-resolution angle-resolved photoemission spectroscopy and density functional theory calculations, we meticulously map the three-dimensional electronic structure of CrSb. Our photoemission spectroscopic results on both (0001) and (10$\overline{1}$0) cleavages of CrSb collaboratively reveal unprecedented details on AM-induced band splitting, and subsequently pin down its unique bulk $g$-wave symmetry through quantitative analysis of the angular and photon-energy dependence of spin splitting. Moreover, the observed spin splitting reaches the magnitude of 0.93~eV near $E_F$, the most substantial among all confirmed AM materials. This study not only validates the nature of CrSb as a prototype $g$-wave like AM material but also underscores its pivotal role in pioneering applications in spintronics.
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Submitted 15 November, 2024; v1 submitted 21 May, 2024;
originally announced May 2024.
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Unveiling the charge density wave mechanism in vanadium-based Bi-layered kagome metals
Authors:
Yi-Chen Yang,
Soohyun Cho,
Tong-Rui Li,
Xiang-Qi Liu,
Zheng-Tai Liu,
Zhi-Cheng Jiang,
Jian-Yang Ding,
Wei Xia,
Zi-Cheng Tao,
Jia-Yu Liu,
Wen-Chuan Jing,
Yu Huang,
Yu-Ming Shi,
Soonsang Huh,
Takeshi Kondo,
Zhe Sun,
Ji-Shan Liu,
Mao Ye,
Yi-Lin Wang,
Yan-Feng Guo,
Da-Wei Shen
Abstract:
The charge density wave (CDW), as a hallmark of vanadium-based kagome superconductor AV3Sb5 (A = K, Rb, Cs), has attracted intensive attention. However, the fundamental controversy regarding the underlying mechanism of CDW therein persists. Recently, the vanadium-based bi-layered kagome metal ScV6Sn6, reported to exhibit a long-range charge order below 94 K, has emerged as a promising candidate to…
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The charge density wave (CDW), as a hallmark of vanadium-based kagome superconductor AV3Sb5 (A = K, Rb, Cs), has attracted intensive attention. However, the fundamental controversy regarding the underlying mechanism of CDW therein persists. Recently, the vanadium-based bi-layered kagome metal ScV6Sn6, reported to exhibit a long-range charge order below 94 K, has emerged as a promising candidate to further clarify this core issue. Here, employing micro-focusing angle-resolved photoemission spectroscopy (μ-ARPES) and first-principles calculations, we systematically studied the unique CDW order in vanadium-based bi-layered kagome metals by comparing ScV6Sn6 with its isostructural counterpart YV6Sn6, which lacks a CDW ground state. Combining ARPES data and the corresponding joint density of states (DOS), we suggest that the VHS nesting mechanism might be invalid in these materials. Besides, in ScV6Sn6, we identified multiple hybridization energy gaps resulting from CDW-induced band folding, along with an anomalous band dispersion, implying a potential electron-phonon coupling driven mechanism underlying the formation of the CDW order. Our finding not only comprehensively maps the electronic structure of V-based bi-layer kagome metals but also provide constructive experimental evidence for the unique origin of CDW in this system.
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Submitted 6 February, 2024;
originally announced February 2024.
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Flat bands, non-trivial band topology and electronic nematicity in layered kagome-lattice RbTi$_3$Bi$_5$
Authors:
Zhicheng Jiang,
Zhengtai Liu,
Haiyang Ma,
Wei Xia,
Zhonghao Liu,
Jishan Liu,
Soohyun Cho,
Yichen Yang,
Jianyang Ding,
Jiayu Liu,
Zhe Huang,
Yuxi Qiao,
Jiajia Shen,
Wenchuan Jing,
Xiangqi Liu,
Jianpeng Liu,
Yanfeng Guo,
Dawei Shen
Abstract:
Layered kagome-lattice materials with 3$d$ transition metals provide a fertile playground for studies on geometry frustration, band topology and other novel ordered states. A representative class of materials AV$_3$Sb$_5$ (A=K, Rb, Cs) have been proved to possess various unconventional phases such as superconductivity, non-trivial $\mathbb{Z}_2$ band topology, and electronic nematicity, which are…
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Layered kagome-lattice materials with 3$d$ transition metals provide a fertile playground for studies on geometry frustration, band topology and other novel ordered states. A representative class of materials AV$_3$Sb$_5$ (A=K, Rb, Cs) have been proved to possess various unconventional phases such as superconductivity, non-trivial $\mathbb{Z}_2$ band topology, and electronic nematicity, which are intertwined with multiple interlaced charge density waves (CDW). However, the interplay among these novel states and their mechanisms are still elusive. Recently, the discovery of isostructural titanium-based single-crystals ATi$_3$Bi$_5$ (A=K, Rb, Cs), which demonstrate similar multiple exotic states but in the absence of the concomitant intertwined CDW, has been offering an ideal opportunity to disentangle these complex novel states in kagome-lattice. Here, we combine the high-resolution angle-resolved photoemission spectroscopy and first-principles calculations to systematically investigate the low-lying electronic structure of RbTi$_3$Bi$_5$. For the first time, we experimentally demonstrate the coexistence of flat bands and multiple non-trivial topological states, including type-II Dirac nodal lines and non-trivial $\mathbb{Z}_2$ topological surface states therein. Furthermore, our findings as well provide the hint of rotation symmetry breaking in RbTi$_3$Bi$_5$, suggesting the directionality of the electronic structure and possibility of emerging pure electronic nematicity in this new family of kagome compounds, which may provide important insights into the electronic nematic phase in correlated kagome metals.
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Submitted 5 December, 2022;
originally announced December 2022.
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The FAST Galactic Plane Pulsar Snapshot survey: I. Project design and pulsar discoveries
Authors:
J. L. Han,
Chen Wang,
P. F. Wang,
Tao Wang,
D. J. Zhou,
Jing-Hai Sun,
Yi Yan,
Wei-Qi Su,
Wei-Cong Jing,
Xue Chen,
X. Y. Gao,
Li-Gang Hou,
Jun Xu,
K. J. Lee,
Na Wang,
Peng Jiang,
Ren-Xin Xu,
Jun Yan,
Heng-Qian Gan,
Xin Guan,
Wen-Jun Huang,
Jin-Chen Jiang,
Hui Li,
Yun-Peng Men,
Chun Sun
, et al. (12 additional authors not shown)
Abstract:
Discovery of pulsars is one of the main goals for large radio telescopes. The Five-hundred-meter Aperture Spherical radio Telescope (FAST), that incorporates an L-band 19-beam receiver with a system temperature of about 20~K, is the most sensitive radio telescope utilized for discovering pulsars. We designed the {\it snapshot} observation mode for a FAST key science project, the Galactic Plane Pul…
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Discovery of pulsars is one of the main goals for large radio telescopes. The Five-hundred-meter Aperture Spherical radio Telescope (FAST), that incorporates an L-band 19-beam receiver with a system temperature of about 20~K, is the most sensitive radio telescope utilized for discovering pulsars. We designed the {\it snapshot} observation mode for a FAST key science project, the Galactic Plane Pulsar Snapshot (GPPS) survey, in which every four nearby pointings can observe {\it a cover} of a sky patch of 0.1575 square degrees through beam-switching of the L-band 19-beam receiver. The integration time for each pointing is 300 seconds so that the GPPS observations for a cover can be made in 21 minutes. The goal of the GPPS survey is to discover pulsars within the Galactic latitude of $\pm10^{\circ}$ from the Galactic plane, and the highest priority is given to the inner Galaxy within $\pm5^{\circ}$. Up to now, the GPPS survey has discovered 201 pulsars, including currently the faintest pulsars which cannot be detected by other telescopes, pulsars with extremely high dispersion measures (DMs) which challenge the currently widely used models for the Galactic electron density distribution, pulsars coincident with supernova remnants, 40 millisecond pulsars, 16 binary pulsars, some nulling and mode-changing pulsars and rotating radio transients (RRATs). The follow-up observations for confirmation of new pulsars have polarization-signals recorded for polarization profiles of the pulsars. Re-detection of previously known pulsars in the survey data also leads to significant improvements in parameters for 64 pulsars. The GPPS survey discoveries are published and will be updated at http://zmtt.bao.ac.cn/GPPS/ .
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Submitted 18 May, 2021;
originally announced May 2021.
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Copper Replaces Tin: A Copper based Gelling Catalyst for Poly-Urethane from Discarded Motherboard
Authors:
Bibudha Parasar,
Gao Wen Jing,
Dandan Yuan,
Wang Kun,
Peng Wang,
Arijit Dasgupta,
Atharva Sahasrabudhe,
Soumitra Barman,
Rongxin Yuan,
Soumyajit Roy
Abstract:
A discarded motherboard based eco-friendly copper catalyst has been programmed to replace the industrially used tin based catalyst DBTDL. The catalyst has been characterized by UV-Vis spectroscopy, FT-IR and TEM. Using the catalyst reaction conditions is optimized and under the optimized condition, both polyurethane and polyurethane foam are prepared, thus proving the generality of the catalyst to…
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A discarded motherboard based eco-friendly copper catalyst has been programmed to replace the industrially used tin based catalyst DBTDL. The catalyst has been characterized by UV-Vis spectroscopy, FT-IR and TEM. Using the catalyst reaction conditions is optimized and under the optimized condition, both polyurethane and polyurethane foam are prepared, thus proving the generality of the catalyst to be used in industries. A possible mechanism has also been proposed.
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Submitted 10 July, 2013;
originally announced July 2013.