Engineering Papers⌕ Search
Home/Archive/DOE OSTI

DOE OSTI · 2586817

Spin excitations and flat electronic bands in a Cr-based kagome superconductor

Wang, Zehao [Rice Univ., Houston, TX (United States)] (ORCID:0009000409861402)·Guo, Yucheng [Rice Univ., Houston, TX (United States)] (ORCID:0000000303721578)·Huang, Hsiao-Yu [National Synchrotron Radiation Research Center, Hsinchu (Taiwan)] (ORCID:0000000208430000)·Xie, Fang [Rice Univ., Houston, TX (United States)]·Huang, Yuefei [Rice Univ., Houston, TX (United States)]·Gao, Bin [Rice Univ., Houston, TX (United States)] (ORCID:0000000228532362)·Oh, Ji Seop [Rice Univ., Houston, TX (United States); Univ. of California, Berkeley, CA (United States); Sookmyung Women’s Univ., Seoul (Korea, Republic of)]·Wu, Han [Rice Univ., Houston, TX (United States)] (ORCID:0000000332325267)·Okamoto, Jun [National Synchrotron Radiation Research Center, Hsinchu (Taiwan)] (ORCID:0000000305386603)·Channagowdra, Ganesha [National Synchrotron Radiation Research Center, Hsinchu (Taiwan)]·Chen, Chien-Te [National Synchrotron Radiation Research Center, Hsinchu (Taiwan)] (ORCID:0000000218812600)·Ye, Feng [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000174774648)·Lu, Xingye [Beijing Normal University, Beijing (China)] (ORCID:0000000204091240)·Liu, Zhaoyu [Univ. of Washington, Seattle, WA (United States)] (ORCID:0000000298949622)·Ren, Zheng [Rice Univ., Houston, TX (United States)] (ORCID:0000000224228216)·Fang, Yuan [Rice Univ., Houston, TX (United States)] (ORCID:0000000198854925)·Wang, Yiming [Rice Univ., Houston, TX (United States)]·Biswas, Ananya [Rice Univ., Houston, TX (United States)]·Zhang, Yichen [Rice Univ., Houston, TX (United States)] (ORCID:000000016792330X)·Yue, Ziqin [Rice Univ., Houston, TX (United States)] (ORCID:0000000332127113)·Hu, Cheng [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)] (ORCID:0000000323357806)·Jozwiak, Chris [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)] (ORCID:0000000209803753)·Bostwick, Aaron [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)] (ORCID:0000000290082980)·Rotenberg, Eli [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)] (ORCID:0000000239798844)·Hashimoto, Makoto [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)] (ORCID:0000000316898997)·Lu, Donghui [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)] (ORCID:0000000297080443)·Kono, Junichiro [Rice Univ., Houston, TX (United States)] (ORCID:0000000241950577)·Chu, Jiun-Haw [Univ. of Washington, Seattle, WA (United States)] (ORCID:0000000162221210)·Yakobson, Boris I. [Rice Univ., Houston, TX (United States)] (ORCID:0000000183693567)·Birgeneau, Robert J. [Univ. of California, Berkeley, CA (United States)] (ORCID:0000000311928333)·Cao, Guang-Han [Zhejiang Univ., Hangzhou (China)] (ORCID:0000000296695761)·Fujimori, Atsushi [National Synchrotron Radiation Research Center, Hsinchu (Taiwan); National Tsing Hua Univ., Hsinchu (Taiwan); Univ. of Tokyo (Japan)] (ORCID:0000000348760634)·Huang, Di-Jing [National Synchrotron Radiation Research Center, Hsinchu (Taiwan); National Tsing Hua Univ., Hsinchu (Taiwan)] (ORCID:0000000347508453)·Si, Qimiao [Rice Univ., Houston, TX (United States)] (ORCID:0000000313572705)·Yi, Ming [Rice Univ., Houston, TX (United States)] (ORCID:0000000189347905)·Dai, Pengcheng [Rice Univ., Houston, TX (United States)] (ORCID:0000000260883170)
View original source ↗Read source document ↗Export metadata ↓

Abstract

In the quest for topology- and correlation-driven quantum states, kagome lattice materials have garnered significant interest for their band structures, featuring flat bands (FBs) from the quantum destructive interference of the electronic wavefunction. Tuning an FB to the chemical potential could induce electronic instabilities and emergent orders. Despite extensive studies, direct evidence of FBs tuned to the chemical potential and their role in emergent orders in bulk materials remains lacking. Using angle-resolved photoemission spectroscopy, resonant inelastic X-ray scattering, and density functional theory, we show that the low-energy structure of the Cr-based kagome metal superconductor CsCr 3 Sb 5 is dominated by FBs at the Fermi level. We also observe low-energy magnetic excitations evolving across the low-temperature transition, largely consistent with the FB shift. Our results suggest that the low-temperature order contains a magnetic origin and that the kagome FBs may play a role in the emergence of this order.

Explore related subjects

electronic properties and materialsmagnetic properties and materials

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Wang, Zehao [Rice Univ., Houston, TX (United States)] (ORCID:0009000409861402), Guo, Yucheng [Rice Univ., Houston, TX (United States)] (ORCID:0000000303721578), Huang, Hsiao-Yu [National Synchrotron Radiation Research Center, Hsinchu (Taiwan)] (ORCID:0000000208430000), Xie, Fang [Rice Univ., Houston, TX (United States)], Huang, Yuefei [Rice Univ., Houston, TX (United States)], Gao, Bin [Rice Univ., Houston, TX (United States)] (ORCID:0000000228532362), Oh, Ji Seop [Rice Univ., Houston, TX (United States); Univ. of California, Berkeley, CA (United States); Sookmyung Women’s Univ., Seoul (Korea, Republic of)], Wu, Han [Rice Univ., Houston, TX (United States)] (ORCID:0000000332325267), Okamoto, Jun [National Synchrotron Radiation Research Center, Hsinchu (Taiwan)] (ORCID:0000000305386603), Channagowdra, Ganesha [National Synchrotron Radiation Research Center, Hsinchu (Taiwan)], Chen, Chien-Te [National Synchrotron Radiation Research Center, Hsinchu (Taiwan)] (ORCID:0000000218812600), Ye, Feng [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000174774648), Lu, Xingye [Beijing Normal University, Beijing (China)] (ORCID:0000000204091240), Liu, Zhaoyu [Univ. of Washington, Seattle, WA (United States)] (ORCID:0000000298949622), Ren, Zheng [Rice Univ., Houston, TX (United States)] (ORCID:0000000224228216), Fang, Yuan [Rice Univ., Houston, TX (United States)] (ORCID:0000000198854925), Wang, Yiming [Rice Univ., Houston, TX (United States)], Biswas, Ananya [Rice Univ., Houston, TX (United States)], Zhang, Yichen [Rice Univ., Houston, TX (United States)] (ORCID:000000016792330X), Yue, Ziqin [Rice Univ., Houston, TX (United States)] (ORCID:0000000332127113), Hu, Cheng [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)] (ORCID:0000000323357806), Jozwiak, Chris [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)] (ORCID:0000000209803753), Bostwick, Aaron [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)] (ORCID:0000000290082980), Rotenberg, Eli [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)] (ORCID:0000000239798844), Hashimoto, Makoto [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)] (ORCID:0000000316898997), Lu, Donghui [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)] (ORCID:0000000297080443), Kono, Junichiro [Rice Univ., Houston, TX (United States)] (ORCID:0000000241950577), Chu, Jiun-Haw [Univ. of Washington, Seattle, WA (United States)] (ORCID:0000000162221210), Yakobson, Boris I. [Rice Univ., Houston, TX (United States)] (ORCID:0000000183693567), Birgeneau, Robert J. [Univ. of California, Berkeley, CA (United States)] (ORCID:0000000311928333), Cao, Guang-Han [Zhejiang Univ., Hangzhou (China)] (ORCID:0000000296695761), Fujimori, Atsushi [National Synchrotron Radiation Research Center, Hsinchu (Taiwan); National Tsing Hua Univ., Hsinchu (Taiwan); Univ. of Tokyo (Japan)] (ORCID:0000000348760634), Huang, Di-Jing [National Synchrotron Radiation Research Center, Hsinchu (Taiwan); National Tsing Hua Univ., Hsinchu (Taiwan)] (ORCID:0000000347508453), Si, Qimiao [Rice Univ., Houston, TX (United States)] (ORCID:0000000313572705), Yi, Ming [Rice Univ., Houston, TX (United States)] (ORCID:0000000189347905), Dai, Pengcheng [Rice Univ., Houston, TX (United States)] (ORCID:0000000260883170). 2025-08-14. Spin excitations and flat electronic bands in a Cr-based kagome superconductor. https://doi.org/10.1038/s41467-025-62298-5

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related reports

DOE OSTI2025

Momentum space AC Josephson effect and intervalley coherence in multilayer graphene

Electron transport driven by the phase coherence and interference of quantum many-body wavefunctions is a fascinating phenomenon with potential technological significance. Superconductivity, for example, enables dissipationless transport through macroscopic phase twisting, while charge-density waves show broadband noise and AC-DC interference once their phase is depinned. We identify an analogous phase-coherent dynamics in the intervalley-coherent (IVC) state frequently observed in rhombohedral multilayer graphene. We show that a static magnetic field drives an oscillating intervalley current, which produces an oscillating orbital magnetization and thereby a detectable AC Hall response. This mechanism is similar to the Josephson effect observed in superconductors but now happening in momentum space. In this analogy, the static magnetic field acts as the DC voltage, while the oscillating intervalley current is the AC Josephson current. We provide microscopic calculations of all the phase-number free-energy parameters in rhombohedral trilayer graphene, establishing this effect as an experimental signature of IVC order.

electronic properties and materials↗
DOE OSTI2025

Field-tunable valley coupling in a dodecagonal semiconductor quasicrystal

Quasicrystals are characterized by atomic arrangements having long-range order without periodicity. Van der Waals bilayers provide an opportunity to controllably vary the atomic alignment between two layers from a periodic moiré crystal to an aperiodic quasicrystal. Here, in this work, we reveal that in a dodecagonal WSe 2 quasicrystal, two separate valleys in separate layers are brought arbitrarily close in momentum space through higher-order Umklapp scatterings. A modest perpendicular electric field is then sufficient to induce strong interlayer valley hybridization, manifested as another hybrid excitonic doublet. Concurrently, we observe the disappearance of the trion that exists at low field, which we attribute to a modified spatial distribution of the wavefunction due to the quasicrystal potential. This is possibly a precursor to localization. Our findings highlight the ability of incommensurate systems to bring any pair of momenta into close proximity, thereby introducing opportunities for valley engineering.

electronic properties and materials↗
DOE OSTI2025

Robust supermoiré pattern in large-angle single-twist bilayers

Forming long-wavelength moiré superlattices in van der Waals bilayers that have a small-angle twist between the two layers has been a key approach for creating moiré flat bands. However, for small twist angles, strong lattice reconstruction creates domain walls and other forms of disorder in the moiré pattern, posing considerable challenges for engineering such platforms. At large twist angles, the lattices are more rigid, but it is difficult to produce flat bands in shorter-wavelength moiré superlattices. Here, in this study, we introduce an approach for tailoring robust supermoiré structures in bilayers of transition-metal dichalcogenides using only a single twist near a commensurate angle. Structurally, we show the spontaneous formation of a periodic arrangement of three inequivalent commensurate moiré stackings, where the angle deviation from the commensurate angle determines the periodicity. Electronically, we reveal a large set of van Hove singularities that indicate strong band hybridization, leading to flat bands near the valence band maximum. Our study extends the study of the interplay among band topology, quantum geometry and moiré superconductivity to the large twist angle regime.

electronic properties and materials↗