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Fumega AO, Lado JL. Nature of the Unconventional Heavy-Fermion Kondo State in Monolayer CeSiI. NANO LETTERS 2024; 24:4272-4278. [PMID: 38394370 PMCID: PMC11010227 DOI: 10.1021/acs.nanolett.4c00619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 02/14/2024] [Accepted: 02/15/2024] [Indexed: 02/25/2024]
Abstract
CeSiI has been recently isolated in the ultrathin limit, establishing CeSiI as the first intrinsic two-dimensional van der Waals heavy-fermion material up to 85 K. We show that, due to the strong spin-orbit coupling, the local moments develop a multipolar real-space magnetic texture, leading to local pseudospins with a nearly vanishing net moment. To elucidate its Kondo-screened regime, we extract from first-principles the parameters of the Kondo lattice model describing this material. We develop a pseudofermion methodology in combination with ab initio calculations to reveal the nature of the heavy-fermion state in CeSiI. We analyze the competing magnetic interactions leading to an unconventional heavy-fermion order as a function of the magnetic exchange between the localized f-electrons and the strength of the Kondo coupling. Our results show that the magnetic exchange interactions promote an unconventional momentum-dependent Kondo-screened phase, establishing the nature of the heavy-fermion state observed in CeSiI.
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Affiliation(s)
- Adolfo O. Fumega
- Department of Applied
Physics, Aalto University, 02150 Espoo, Finland
| | - Jose L. Lado
- Department of Applied
Physics, Aalto University, 02150 Espoo, Finland
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Kyrk TM, Kennedy ER, Galeano-Cabral J, McCandless GT, Scott MC, Baumbach RE, Chan JY. Much more to explore with an oxidation state of nearly four: Pr valence instability in intermetallic m-Pr 2Co 3Ge 5. SCIENCE ADVANCES 2024; 10:eadl2818. [PMID: 38277457 PMCID: PMC10816709 DOI: 10.1126/sciadv.adl2818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 12/27/2023] [Indexed: 01/28/2024]
Abstract
For some intermetallic compounds containing lanthanides, structural transitions can result in intermediate electronic states between trivalency and tetravalency; however, this is rarely observed for praseodymium compounds. The dominant trivalency of praseodymium limits potential discoveries of emergent quantum states in itinerant 4f1 systems accessible using Pr4+-based compounds. Here, we use in situ powder x-ray diffraction and in situ electron energy-loss spectroscopy (EELS) to identify an intermetallic example of a dominantly Pr4+ state in the polymorphic system Pr2Co3Ge5. The structure-valence transition from a nearly full Pr4+ electronic state to a typical Pr3+ state shows the potential of Pr-based intermetallic compounds to host valence-unstable states and provides an opportunity to discover previously unknown quantum phenomena. In addition, this work emphasizes the need for complementary techniques like EELS when evaluating the magnetic and electronic properties of Pr intermetallic systems to reveal details easily overlooked when relying on bulk magnetic measurements alone.
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Affiliation(s)
- Trent M. Kyrk
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706, USA
| | - Ellis R. Kennedy
- Department of Materials Science and Engineering, Univeristy of California, Berkeley, Berkeley, CA 94720, USA
| | - Jorge Galeano-Cabral
- FAMU-FSU College of Engineering, Department of Mechanical Engineering, Florida State University, Tallahassee, FL 32310, USA
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
| | | | - Mary C. Scott
- Department of Materials Science and Engineering, Univeristy of California, Berkeley, Berkeley, CA 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Ryan E. Baumbach
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
- Department of Physics, Florida State University, Tallahassee, FL 32310, USA
| | - Julia Y. Chan
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76706, USA
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Fuhrman WT, Sidorenko A, Hänel J, Winkler H, Prokofiev A, Rodriguez-Rivera JA, Qiu Y, Blaha P, Si Q, Broholm CL, Paschen S. Pristine quantum criticality in a Kondo semimetal. SCIENCE ADVANCES 2021; 7:eabf9134. [PMID: 34138738 PMCID: PMC8133744 DOI: 10.1126/sciadv.abf9134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
The observation of quantum criticality in diverse classes of strongly correlated electron systems has been instrumental in establishing ordering principles, discovering new phases, and identifying the relevant degrees of freedom and interactions. At focus so far have been insulators and metals. Semimetals, which are of great current interest as candidate phases with nontrivial topology, are much less explored in experiments. Here, we study the Kondo semimetal CeRu4Sn6 by magnetic susceptibility, specific heat, and inelastic neutron scattering experiments. The power-law divergence of the magnetic Grünesien ratio reveals that, unexpectedly, this compound is quantum critical without tuning. The dynamical energy over temperature scaling in the neutron response throughout the Brillouin zone and the temperature dependence of the static uniform susceptibility, indicate that temperature is the only energy scale in the criticality. Such behavior, which has been associated with Kondo destruction quantum criticality in metallic systems, could be generic in the semimetal setting.
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Affiliation(s)
- Wesley T Fuhrman
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Andrey Sidorenko
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Jonathan Hänel
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Hannes Winkler
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Andrey Prokofiev
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Jose A Rodriguez-Rivera
- Department of Materials Sciences, University of Maryland, College Park, MD 20742, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Yiming Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Peter Blaha
- Institute of Materials Chemistry, Vienna University of Technology, 1040 Vienna, Austria
| | - Qimiao Si
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, USA
| | - Collin L Broholm
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Silke Paschen
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria.
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, USA
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