1
|
Frontini F, Lebert BW, Cho KK, Song MS, Cho BK, Pollock CJ, Kim YJ. Intermediate valence state in YbB 4revealed by resonant x-ray emission spectroscopy. J Phys Condens Matter 2022; 34:345601. [PMID: 35667370 DOI: 10.1088/1361-648x/ac7629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/06/2022] [Indexed: 06/15/2023]
Abstract
We report the temperature dependence of the Yb valence in the geometrically frustrated compoundYbB4from 12 to 300 K using resonant x-ray emission spectroscopy at the YbLα1transition. We find that the Yb valence,v, is hybridized between thev = 2 andv = 3 valence states, increasing fromv=2.61±0.01at 12 K tov=2.67±0.01at 300 K, confirming thatYbB4is a Kondo system in the intermediate valence regime. This result indicates that the Kondo interaction inYbB4is substantial, and is likely to be the reason whyYbB4does not order magnetically at low temperature, rather than this being an effect of geometric frustration. Furthermore, the zero-point valence of the system is extracted from our data and compared with other Kondo lattice systems. The zero-point valence seems to be weakly dependent on the Kondo temperature scale, but not on the valence change temperature scaleTv.
Collapse
Affiliation(s)
- Felix Frontini
- Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7, Canada
| | - Blair W Lebert
- Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7, Canada
| | - K K Cho
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 61005 Gwangju, Republic of Korea
| | - M S Song
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 61005 Gwangju, Republic of Korea
| | - B K Cho
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology, 61005 Gwangju, Republic of Korea
| | - Christopher J Pollock
- Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853, United States of America
| | - Young-June Kim
- Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7, Canada
| |
Collapse
|
2
|
O'Neill CD, Schmehr JL, Keen HDJ, Pritchard Cairns L, Sokolov DA, Hermann A, Wermeille D, Manuel P, Krüger F, Huxley AD. Non-Fermi liquid behavior below the Néel temperature in the frustrated heavy fermion magnet UAu 2. Proc Natl Acad Sci U S A 2021; 118:e2102687118. [PMID: 34873053 DOI: 10.1073/pnas.2102687118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2021] [Indexed: 11/18/2022] Open
Abstract
The term Fermi liquid is almost synonymous with the metallic state. The association is known to break down at quantum critical points (QCPs), but these require precise values of tuning parameters, such as pressure and applied magnetic field, to exactly suppress a continuous phase transition temperature to the absolute zero. Three-dimensional non-Fermi liquid states, apart from superconductivity, that are unshackled from a QCP are much rarer and are not currently well understood. Here, we report that the triangular lattice system uranium diauride (UAu2) forms such a state with a non-Fermi liquid low-temperature heat capacity [Formula: see text] and electrical resistivity [Formula: see text] far below its Néel temperature. The magnetic order itself has a novel structure and is accompanied by weak charge modulation that is not simply due to magnetostriction. The charge modulation continues to grow in amplitude with decreasing temperature, suggesting that charge degrees of freedom play an important role in the non-Fermi liquid behavior. In contrast with QCPs, the heat capacity and resistivity we find are unusually resilient in magnetic field. Our results suggest that a combination of magnetic frustration and Kondo physics may result in the emergence of this novel state.
Collapse
|
3
|
Tuerhong R, Boero M, Bucher JP. Molecular attachment to a microscope tip: inelastic tunneling, Kondo screening, and thermopower. Beilstein J Nanotechnol 2019; 10:1243-1250. [PMID: 31293862 PMCID: PMC6604733 DOI: 10.3762/bjnano.10.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/06/2019] [Indexed: 06/09/2023]
Abstract
The vibrational excitation related transport properties of a manganese phthalocyanine molecule suspended between the tip of a scanning tunneling microsope (STM) and a surface are investigated by combining the local manipulation capabilities of the STM with inelastic electron tunneling spectroscopy. By attachment of the molecule to the probe tip, the intrinsic physical properties similar to those exhibited by a free standing molecule become accessible. This technique allows one to study locally the magnetic properties, as well as other elementary excitations and their mutual interaction. In particular a clear correlation is observed between the Kondo resonance and the vibrations with a strong incidence of the Kondo correlation on the thermopower measured across the single-molecule junction.
Collapse
Affiliation(s)
| | - Mauro Boero
- Université de Strasbourg, IPCMS UMR 70504, 67034 Strasbourg, France
| | | |
Collapse
|
4
|
Janoschek M, Das P, Chakrabarti B, Abernathy DL, Lumsden MD, Lawrence JM, Thompson JD, Lander GH, Mitchell JN, Richmond S, Ramos M, Trouw F, Zhu JX, Haule K, Kotliar G, Bauer ED. The valence-fluctuating ground state of plutonium. Sci Adv 2015; 1:e1500188. [PMID: 26601219 PMCID: PMC4646783 DOI: 10.1126/sciadv.1500188] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/12/2015] [Indexed: 06/01/2023]
Abstract
A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such electronic correlations frequently arise because of the competition of localized and itinerant electronic degrees of freedom. Although the respective limits of well-localized or entirely itinerant ground states are well understood, the intermediate regime that controls the functional properties of complex materials continues to challenge theoretical understanding. We have used neutron spectroscopy to investigate plutonium, which is a prototypical material at the brink between bonding and nonbonding configurations. Our study reveals that the ground state of plutonium is governed by valence fluctuations, that is, a quantum mechanical superposition of localized and itinerant electronic configurations as recently predicted by dynamical mean field theory. Our results not only resolve the long-standing controversy between experiment and theory on plutonium's magnetism but also suggest an improved understanding of the effects of such electronic dichotomy in complex materials.
Collapse
Affiliation(s)
- Marc Janoschek
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Pinaki Das
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Bismayan Chakrabarti
- Department of Physics and Astronomy and Center for Condensed Matter Theory, Rutgers University, Piscataway, NJ 08854–8019, USA
| | - Douglas L. Abernathy
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831–6475, USA
| | - Mark D. Lumsden
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831–6475, USA
| | | | | | - Gerard H. Lander
- European Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, D-76125 Karlsruhe, Germany
| | | | - Scott Richmond
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Mike Ramos
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Frans Trouw
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Jian-Xin Zhu
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Kristjan Haule
- Department of Physics and Astronomy and Center for Condensed Matter Theory, Rutgers University, Piscataway, NJ 08854–8019, USA
| | - Gabriel Kotliar
- Department of Physics and Astronomy and Center for Condensed Matter Theory, Rutgers University, Piscataway, NJ 08854–8019, USA
| | - Eric D. Bauer
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| |
Collapse
|