An alternative view at the zero-bias anomaly of metallic point contacts

Gloos, K.

doi:10.1063/1.3274810

Cited by 13 publications

(11 citation statements)

References 27 publications

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“…Such a possibility was mentioned -but discarded -by Chalsani et al [9] for Pb -Cu contacts. Nevertheless, this speculation could be supported by recent experiments on the size-dependence of the so-called zero-bias anomaly which has been attributed to the spontaneous electron spin polarization at the point contact [18].…”

Section: Discussionmentioning

confidence: 89%

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Andreev-reflection spectroscopy of ferromagnets: The impact of Fermi surface mismatch

Tuuli

Gloos

2011

Low Temperature Physics

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We have investigated point contacts between a superconductor (Nb, AuIn 2 ) and a normal metal (ferromagnetic Co, non-magnetic Cu). The observed Andreev-reflection spectra were analyzed using the modified BTK theory including spin-polarization effects. This resulted in a polarization of Co that agrees with observations by others, but lifetime effects describe the spectra equally well. On the other hand, the spectra with non-magnetic Cu can be well described using the spin-polarization model. The ambiguity between polarization and lifetime interpretation poses a dilemma which can be resolved by considering the normal reflection at those interfaces due to Fermi surface mismatch. Our data suggest that Andreev reflection at Nb -Co contacts does deliver the true magnetic polarization of Co only when lifetime effects and the above mentioned intrinsic normal reflection are included.

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Section: Discussionmentioning

confidence: 89%

“…The origin of the side peaks will be discussed elsewhere. Contacts of type iv) were studied earlier [18].…”

Section: Methodsmentioning

confidence: 99%

Andreev-reflection spectroscopy of ferromagnets: The impact of Fermi surface mismatch

Tuuli

Gloos

2011

Low Temperature Physics

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“…In particular in the situation when the off-resonance conductance outside the energy range of the ZBA is relatively high or 0 0.1 G G alternative interpretations have to be considered [16]. On the other hand many ZBAs observed in point contacts that remained unexplained at the time of their observation have now been re-discussed in the framework of Kondo physics due to the presence of a spontaneous spin polarization [25].…”

Section: Introductionmentioning

confidence: 99%

Switchable zero-bias anomaly in individual C60 molecules contacted with tunable aluminum electrodes

Scheer

Böhler

Edtbauer

et al. 2013

Low Temperature Physics

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We report the observation of strong resonances at zero bias in the differential conductance through Al-C 60 -Al junctions with tunable electrode distance, measured above T = 10 K. The conductance value at resonance ranges from a few percent up to eighty percent of the quantum of conductance. The resonances may disappear or reoccur completely and discontinuously upon very small changes of the electrode distance. However, once they are formed they are very robust with respect to changes of the electrode distance. We discuss similarities and differences to the common theories of the Kondo screening of a spontaneous spin polarization of the C 60 molecule. We deduce Kondo temperatures in the range from 35 to 160 K and demonstrate that the temperature dependence is in agreement with the scaling behavior of the Kondo effect in the temperature range of our experiment.

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“…13,14 Over time various models for Kondo scattering without magnetic impurities have been proposed to explain pointcontact studies ranging from tunneling into two-level tunneling systems coupled strongly to the conduction electrons 15 to localized electron spins at the point contact. 16 Very recently, Maltseva et al 17 presented a theory for electron cotunneling into a dense Kondo lattice that can account for a Fano line shape in the conductance. Also Yang 18 argued that the PCS spectra for CeCoIn 5 are consistent with a two-fluid picture based on the Kondo lattice scenario.…”

Section: Introductionmentioning

confidence: 99%

Point-contact spectroscopy in heavy-fermion superconductors

et al. 2010

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We develop a microscopic model to calculate point-contact spectra between a metallic tip and a superconducting heavy-fermion system. We apply our tunneling model to the heavy fermion CeCoIn 5 , both in the normal and superconducting states. In point contact and scanning tunneling spectroscopy many heavy-fermion materials, such as CeCoIn 5 , exhibit an asymmetric differential conductance, dI / dV, combined with a strongly suppressed Andreev reflection signal in the superconducting state. We argue that both features may be explained in terms of a multichannel tunneling model in the presence of localized states near the interface. We find that it is not sufficient to tunnel into two itinerant bands of light and heavy electrons to explain the Fano line shape of the differential conductance. Localized states in the bulk or near the interface are an essential component for quantum interference to occur when an electron tunnels from the metallic tip of the point contact into the heavy-fermion system.

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An alternative view at the zero-bias anomaly of metallic point contacts

Cited by 13 publications

References 27 publications

Andreev-reflection spectroscopy of ferromagnets: The impact of Fermi surface mismatch

Andreev-reflection spectroscopy of ferromagnets: The impact of Fermi surface mismatch

Switchable zero-bias anomaly in individual C60 molecules contacted with tunable aluminum electrodes

Point-contact spectroscopy in heavy-fermion superconductors

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