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Patra A, Maity KP, Kamble RB, Prasad V. Tuning spin one channel to exotic orbital two-channel Kondo effect in ferrimagnetic composites of LaNiO 3 and CoFe 2O 4. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:375701. [PMID: 30079891 DOI: 10.1088/1361-648x/aad836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report the tuning from spin one channel to orbital two-channel Kondo (2CK) effect by varying CoFe2O4 (CFO) content in the composites with LaNiO3 (LNO) along with the presence of ferrimagnetism. Although there is no signature of resistivity upturn in the case of pure LNO, all the composites exhibit a distinct upturn in the temperature range of 30-80 K. For composites with lower percentage of CFO (10%), the electron spin plays the key role in the emergence of resistivity upturn which is affected by external magnetic field. On the other hand, when the CFO content is increased (⩾15%), the upturn shows strong robustness against high magnetic field (⩽14 T) and a crossover in temperature variation from [Formula: see text] to T 1/2 at the Kondo temperature, indicating the appearance of orbital 2CK effect. The orbital 2CK effect originates due to the scattering of conduction electrons from the structural two-level systems which is created at the interfaces between the two phases (LNO and CFO) of different crystal structures as well as inside the crystal planes. The specific heat data at low temperature (⩽40 K), deviates from the usual linear temperature variation of the electronic contribution. With higher CFO content it shows more deviation which also indicates the increasing amount of two-level system. A negative magnetoresistance (MR) is observed at low temperature (<30 K) for composites containing both lower (10%) and higher percentage (15%) of CFO. We have analyzed the negative MR using Khosla and Fisher semi-empirical model based on spin dependent scattering of conduction electrons from localized spins.
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Affiliation(s)
- Ananya Patra
- Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka, India
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Zhu L, Woltersdorf G, Zhao J. Observation of orbital two-channel Kondo effect in a ferromagnetic L1 0-MnGa film. Sci Rep 2016; 6:34549. [PMID: 27686323 PMCID: PMC5043353 DOI: 10.1038/srep34549] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 09/15/2016] [Indexed: 11/09/2022] Open
Abstract
The experimental existence and stability of the fixed point of the two-channel Kondo (2CK) effect displaying exotic non-Fermi liquid physics have been buried in persistent confusion despite the intensive theoretical and experimental efforts in past three decades. Here we report an experimental realization of the two-level system resonant scattering-induced orbital 2CK effect in a ferromagnetic L10-MnGa film, which is signified by a magnetic field-independent resistivity upturn that has a logarithmic and a square-root temperature dependence beyond and below the Kondo temperature of ~14.5 K, respectively. Our results not only evidence the robust existence of orbital 2CK effect even in the presence of strong magnetic fields and long-range ferromagnetic ordering, but also extend the scope of 2CK host materials from nonmagnetic nanoscale point contacts to diffusive conductors of disordered alloys.
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Affiliation(s)
- Lijun Zhu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083, China.,Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 3, Halle 06120, Germany
| | - Georg Woltersdorf
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, von-Danckelmann-Platz 3, Halle 06120, Germany
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083, China
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Arnold M, Langenbruch T, Kroha J. Stable two-channel Kondo fixed point of an SU(3) quantum defect in a metal: renormalization-group analysis and conductance spikes. PHYSICAL REVIEW LETTERS 2007; 99:186601. [PMID: 17995425 DOI: 10.1103/physrevlett.99.186601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2007] [Indexed: 05/25/2023]
Abstract
We propose a physical realization of the two-channel Kondo (2CK) effect, where a dynamical defect in a metal has a unique ground state and twofold degenerate excited states. In a wide range of parameters the interactions with the electrons renormalize the excited doublet downward below the bare defect ground state, thus stabilizing the 2CK fixed point. In addition to the Kondo temperature T(K) the three-state defect exhibits another low-energy scale, associated with ground-to-excited-state transitions, which can be exponentially smaller than T(K). Using the perturbative nonequilibrium renormalization group we demonstrate that this can provide the long-sought explanation of the sharp conductance spikes observed by Ralph and Buhrman in ultrasmall metallic point contacts.
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Affiliation(s)
- Michael Arnold
- Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany
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Thijssen WHA, Djukic D, Otte AF, Bremmer RH, van Ruitenbeek JM. Vibrationally induced two-level systems in single-molecule junctions. PHYSICAL REVIEW LETTERS 2006; 97:226806. [PMID: 17155829 DOI: 10.1103/physrevlett.97.226806] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Indexed: 05/12/2023]
Abstract
Single-molecule junctions are found to show anomalous spikes in dI/dV spectra. The position in energy of the spikes is related to local vibration mode energies. A model of vibrationally induced two-level systems reproduces the data very well. This mechanism is expected to be quite general for single-molecule junctions. It acts as an intrinsic amplification mechanism for local vibration mode features and may be exploited as a new spectroscopic tool.
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Affiliation(s)
- W H A Thijssen
- Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
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Ghosh A, Wright MH, Siegert C, Pepper M, Farrer I, Ford CJB, Ritchie DA. Zero-bias anomaly and kondo-assisted quasiballistic 2D transport. PHYSICAL REVIEW LETTERS 2005; 95:066603. [PMID: 16090970 DOI: 10.1103/physrevlett.95.066603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Revised: 04/18/2005] [Indexed: 05/03/2023]
Abstract
Nonequilibrium transport measurements in mesoscopic quasiballistic 2D electron systems show an enhancement in the differential conductance around the Fermi energy. At very low temperatures, such a zero-bias anomaly splits, leading to a suppression of linear transport at low energies. We also observed a scaling of the nonequilibrium characteristics at low energies which resembles electron scattering by two-state systems, addressed in the framework of two-channel Kondo model. Detailed sample-to-sample reproducibility indicates an intrinsic phenomenon in unconfined 2D systems in the low electron-density regime.
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Affiliation(s)
- A Ghosh
- Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom
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Cichorek T, Sanchez A, Gegenwart P, Weickert F, Wojakowski A, Henkie Z, Auffermann G, Paschen S, Kniep R, Steglich F. Two-channel Kondo effect in glasslike ThAsSe. PHYSICAL REVIEW LETTERS 2005; 94:236603. [PMID: 16090491 DOI: 10.1103/physrevlett.94.236603] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Indexed: 05/03/2023]
Abstract
We present low-temperature heat and charge transport as well as caloric properties of a ThAsSe single crystal. An extra -AT(1/2) term in the electrical resistivity, independent of magnetic fields as high as 14 T, provides evidence for an unusual scattering of conduction electrons. Additionally, both the thermal conductivity and the specific heat show a glass-type temperature dependence which signifies the presence of tunneling states. These observations apparently point to an experimental realization of a two-channel Kondo effect derived from structural two-level systems.
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Affiliation(s)
- T Cichorek
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
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Oreg Y, Goldhaber-Gordon D. Two-channel Kondo effect in a modified single electron transistor. PHYSICAL REVIEW LETTERS 2003; 90:136602. [PMID: 12689314 DOI: 10.1103/physrevlett.90.136602] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2002] [Indexed: 05/24/2023]
Abstract
We suggest a simple system of two electron droplets which should display two-channel Kondo behavior at experimentally accessible temperatures. Stabilization of the two-channel Kondo fixed point requires fine control of the electrochemical potential in each droplet, which can be achieved by adjusting voltages on nearby gate electrodes. We study the conditions for obtaining this type of two-channel Kondo behavior, discuss the experimentally observable consequences, and explore the generalization to the multichannel Kondo case.
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Affiliation(s)
- Yuval Oreg
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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König J, Schmid J, Schoeller H, Schön G. Resonant tunneling through ultrasmall quantum dots: Zero-bias anomalies, magnetic-field dependence, and boson-assisted transport. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:16820-16837. [PMID: 9985812 DOI: 10.1103/physrevb.54.16820] [Citation(s) in RCA: 130] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Zaránd G. Low Energy Properties of M-State Tunneling Systems in Metals: New Candidates for Non-Fermi-Liquid Systems. PHYSICAL REVIEW LETTERS 1996; 77:3609-3612. [PMID: 10062263 DOI: 10.1103/physrevlett.77.3609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Keijsers RJ, Shklyarevskii OI. Point-Contact Study of Fast and Slow Two-Level Fluctuators in Metallic Glasses. PHYSICAL REVIEW LETTERS 1996; 77:3411-3414. [PMID: 10062213 DOI: 10.1103/physrevlett.77.3411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Chun K, Birge NO. Dissipative quantum tunneling of a single defect in a disordered metal. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:4629-4637. [PMID: 9986421 DOI: 10.1103/physrevb.54.4629] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Zaránd G, Vladár K. Low temperature dynamics of an Nf-flavor two level system in a metal: Equivalence with the Nf-channel Kondo model to 1/N2f order. PHYSICAL REVIEW LETTERS 1996; 76:2133-2136. [PMID: 10060614 DOI: 10.1103/physrevlett.76.2133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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König J, Schoeller H, Schön G. Zero-bias anomalies and boson-assisted tunneling through quantum dots. PHYSICAL REVIEW LETTERS 1996; 76:1715-1718. [PMID: 10060499 DOI: 10.1103/physrevlett.76.1715] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Zaránd G. Tunneling of a heavy particle with spin in a metal. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:13459-13470. [PMID: 9980540 DOI: 10.1103/physrevb.52.13459] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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