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Cichorek, T.; Bochenek, Ł.; Schmidt, Marcus; Czulucki, Andreas; Auffermann, Gudrun; Kniep, Rüdiger; Niewa, Rainer; Steglich, F.; Kirchner, Stefan

doi:10.1103/physrevlett.117.106601

Cited by 21 publications

(13 citation statements)

References 46 publications

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“…In this case, the orbital quantum number of the scatterers play the role of (pseudo) spin and the spin degeneracy (up and down) of conduction electrons form the two channels. The TLS may arise from the positional disorder in metallic glasses [17] or due to the local distortion created as a result of the Jahn-Teller effect [18] or by the presence of non-magnetic disorder in the crystals [19]. The orbital 2CK effect depends on the symmetry and the strength of coupling (J) between conduction electrons and the TLS, the tunnelling rate of the atom and the imbalance of electron density in the two channels.…”

Section: Introductionmentioning

confidence: 99%

“…However, Zaránd pointed that if the electrons interact with the TLS through resonant scattering then the strong coupling regime is reached and thus the orbital 2CK effect can be achieved [21]. In addition, many groups have reported the experimental demonstration of orbital 2CK effect due to the electron scattering from structural disorder as illustrated by the TLS model [18,20,[24][25][26][27]. For example, Cichorek et al reported an ln T variation of resistivity in glass-like single crystal ThAsSe which is not affected by the strong magnetic field (⩽17 T) or high hydrostatic pressure (⩽1.88 GPa).…”

Section: Introductionmentioning

confidence: 99%

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Tuning spin one channel to exotic orbital two-channel Kondo effect in ferrimagnetic composites of LaNiO₃ and CoFe₂O₄

Patra

Maity

Kamble

et al. 2018

J. Phys.: Condens. Matter

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We report the tuning from spin one channel to orbital two-channel Kondo (2CK) effect by varying CoFeO (CFO) content in the composites with LaNiO (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 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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tuning spin one channel to exotic orbital two-channel Kondo effect in ferrimagnetic composites of LaNiO₃ and CoFe₂O₄

Patra

Maity

Kamble

et al. 2018

J. Phys.: Condens. Matter

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“…As a consequence, the system may undergo a quantum phase transition driven by the channel asymmetry at zero temperature. Experimental observations of the 2CK and three-channel Kondo effect were also obtained [34][35][36][37][38][39][40][41] . Recently, the Kondo effect involved in the topological systems, including the single-impurity Kondo effect and the 2CK effect, has attracted extensive concerns.…”

Section: Introductionmentioning

confidence: 75%

Natural orbitals renormalization group approach to a Kondo singlet

Zheng

2020

Sci. China Phys. Mech. Astron.

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Using the natural orbitals renormalization group, we studied the problem of a localized spin-1 2 impurity coupled to two helical liquids via the Kondo interaction in a quantum spin Hall insulator, based on the Kane-Mele model defined in a finite zigzag graphene nanoribbon. We investigated the influence of the Kondo couplings with the helical liquids on both the static and dynamic properties of the ground state. The number and distinct spatial structures of the active natural orbitals (ANOs), which play essential roles in constructing the ground-state wave function, were first analyzed. Our numerical results indicate that two ANOs emerge, equal to the number of helical liquids. Specifically, at the coupling symmetry point, both ANOs are fully active with their spatial structures being respectively constituted by the different helical liquids. In comparison, when deviating from the symmetry point, only one ANO remains fully active, which is dominantly constructed by the helical liquid with the larger Kondo coupling. Local screening of the impurity, described by the impurity spin polarization and susceptibility, was further studied. It shows that at the coupling symmetry point, the impurity is maximally polarized and the spin susceptibility reaches the maximum. On the contrary, the impurity tends to be screened without polarization when the Kondo couplings deviate well from the symmetry point. The Kondo screening cloud, manifested by the spin correlation between the impurity and the conduction electrons, was finally explored. It is demonstrated that the Kondo cloud is mainly formed by the helical liquid with the larger Kondo coupling to the impurity. On the other hand, the spin-orbital coupling breaks the symmetry in spatial distribution of the spin correlation, leading to anisotropy in the Kondo cloud.

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“…Given the fact that the vanishing of the R(T) minimum under the application of an external magnetic is one of the typical features of the classical Kondo effect [ 19 , 34 ], we have studied the influence of the magnetic field on the R(T) dependence for all the samples, applying magnetic fields in the range from 10 to 50 kOe (see Figure 7 ). We find two different behaviors in our samples: the minimum observed in the sample Co3sp is negligibly affected by the magnetic field (before and after annealing), whereas in the case of the sample Co9sp, the minimum disappears as we apply the magnetic field (even under the lower applied field of 10 kOe).…”

Section: Resultsmentioning

confidence: 99%

Magneto-Transport Properties of Co–Cu Thin Films Obtained by Co-Sputtering and Sputter Gas Aggregation

et al. 2021

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Cu100−xCox thin films have been obtained by sputtering (x = 3, 9) and sputter gas aggregation (x = 2.5, 7.5) and subsequent annealing at 400 °C for 1 h. We have studied their structural, magnetic, and magnetotransport properties, both for the as-deposited and annealed samples, confirming the important role of the fabrication method in the properties. The magnetic measurements and the fitting of the hysteresis loops evidence that as-deposited samples consist of superparamagnetic (SPM) and/or ferromagnetic clusters, but in the samples obtained by gas aggregation the clusters are greater (with ferromagnetic behavior at room temperature) whereas in the samples obtained by sputtering, the clusters are smaller and there are also diluted Co atoms in the Cu matrix. The annealing affects negligibly the samples obtained by gas aggregation, but the ones obtained by sputtering are more affected, appearing greater clusters. This behavior is also reflected in the magnetoresistance (MR) measurements of the samples, with different shapes of the MR curves depending on the preparation method: more lineal in the whole range for sputtering, saturation at low fields (about 10 kOe) for gas aggregation. Finally, a Kondo-like minimum in the resistance versus temperature is found in the samples obtained by sputtering, affected by the magnetic field and the annealing. The observed Kondo-like behavior and the influence of annealing on a Kondo-like minimum in sputtered thin films have been attributed to the presence of diluted Co atoms in the Cu matrix and the Co precipitations from the Co–Cu solid solution upon annealing respectively.

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Two-Channel Kondo Physics due to As Vacancies in the Layered CompoundZrAs1.58Se0.39

Cited by 21 publications

References 46 publications

Tuning spin one channel to exotic orbital two-channel Kondo effect in ferrimagnetic composites of LaNiO₃ and CoFe₂O₄

Tuning spin one channel to exotic orbital two-channel Kondo effect in ferrimagnetic composites of LaNiO₃ and CoFe₂O₄

Natural orbitals renormalization group approach to a Kondo singlet

Magneto-Transport Properties of Co–Cu Thin Films Obtained by Co-Sputtering and Sputter Gas Aggregation

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Two-Channel Kondo Physics due to As Vacancies in the Layered CompoundZrAs1.58Se0.39

Cited by 21 publications

References 46 publications

Tuning spin one channel to exotic orbital two-channel Kondo effect in ferrimagnetic composites of LaNiO3 and CoFe2O4

Tuning spin one channel to exotic orbital two-channel Kondo effect in ferrimagnetic composites of LaNiO3 and CoFe2O4

Natural orbitals renormalization group approach to a Kondo singlet

Magneto-Transport Properties of Co–Cu Thin Films Obtained by Co-Sputtering and Sputter Gas Aggregation

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Tuning spin one channel to exotic orbital two-channel Kondo effect in ferrimagnetic composites of LaNiO₃ and CoFe₂O₄

Tuning spin one channel to exotic orbital two-channel Kondo effect in ferrimagnetic composites of LaNiO₃ and CoFe₂O₄