Singularities in d2V/dI2 dependences of point contacts between ferromagnetic metals

Verkin, B. I.; Yanson, I. K.; Kulik, I. O.; Shklyarevski, O.I.; Lysykh, A. A.; Naydyuk, Yu.G.

doi:10.1016/0038-1098(79)90337-5

Cited by 81 publications

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“…1d appears at about eV m Ӎ3.63k B T m ). 17 Similar peculiarities in the PC d 2 V/dI 2 spectra of superconductors appear if the average concentration of quasiparticle excitations exceeds a critical value, destroying the superconducting order parameter in the contact region. It was found 19 that the voltage positions of these ''N''-type features tend to coincide with the characteristic energies of slow phonons in a superconductor.…”

Section: ͑Tӎ0͒ ͑2͒mentioning

confidence: 96%

“…In the thermal regime the PCS-spectrum of an Einstein oscillator ប 0 looks like a smeared step with a shallow maximum at eVϭ1.09ប 0 . 17,18 In Figs. 1a and 1b the point-contact spectra of the electron interaction with an Einstein phonon-mode are shown schematically for, respectively, the spectroscopic ͑either ballistic or diffusive͒ and the thermal regimes.…”

Section: ͑Tӎ0͒ ͑2͒mentioning

confidence: 99%

“…The resulting N-shaped structure in the PC spectra is similar to that found in the point contacts with the ferromagnetic metals of the iron group, where the magnetic transition is driven by Joule heating of the contact region at much larger biases. 17 Quantitatively, for a slow boson subsystem it is possible to be heated up to a temperature рT 0 ϳ(eV/4k B ) without temperature smearing of the electron distribution. 20 The steep rise of the contact resistance that occurs at about 5 mV then corresponds to T 0 , which is roughly equal to the temperature at which the magnetic order is destroyed.…”

Section: The Origin Of the Spectral Structurementioning

confidence: 99%

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Point-contact-spectroscopy evidence of quasi-particle interactions in RNi2B2C (R=Ho, Y)

Yanson

Fisun

Jansen

et al. 1997

Low Temperature Physics

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The point-contact (PC) d2V/dI2-spectra of HoNi2B2C and YNl2B2C reveal structure at applied voltages corresponding to the phonon frequencies. At about 4 meV a maximum is observed in the phonondensity of states by analogy to the soft-phonon structure in neutron scattering experiments for LuNi2B2C [P. Dervenagas et al., Phys. Rev. B52, R9839 (1995)]and YNl2B2C [H. Kawano et al., Czech. J. Phys. 46, S2-825 (1996), Phys. Rev. Lett.77, 4628 (1996)]. In the Ho compound the low-energy phonon peak is suppressed by an applied magnetic field in an anisotropic way, pointing to an interaction between the phonons and the magnetic systems. Surprisingly, in the nonmagnetic Y compound the 4-meV peak is also suppressed by a magnetic field. In the Ho-compound contacts which show the 〈quasi-thermal〉 behavior, the detailed magnetic-field and temperature dependences of PC spectra suggest that the magnetic order is destroyed due to the coupled phonon-magnon subsystem which is driven out of equilibrium by electrons that pass through the contact, by analogy with the nonequilibrium phonon-induced destruction of the superconducting state in point contacts [I. K. Yanson et al., JETP Lett. 45, 543 (1987)]. The PC electron-phonon interaction(EPI) spectral functions are reconstructed and the estimates for the λ-parameter yield the values of the order of 0.1. Comparison with PC EPI spectra of nonsuperconducting and nonmagnetic LaNi2B2C. [I. K. Yanson et al., Phys. Rev. Lett. 78, 935 (1997)], as well as the comparative study of PC EPI and Andreev-reflection spectra for various contacts with superconducting Ho and Y compounds suggest that the low-energy part of the electron-quasi-particle interaction spectral function is responsible for the Cooper pairing in these materials. KeywordsPhonon electron interactions, Phonons, Superconducting compounds, Magnetic fields, Point contacts Disciplines Condensed Matter Physics CommentsThe following article appeared in Low Temperature Physics 23 (1997): 712 and may be found at http://dx.doi.org/10.1063/1.593378. RightsCopyright 1997 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The point-contact ͑PC͒ d 2 V/dI 2 -spectra of HoNi 2 B 2 C and YNl 2 B 2 C reveal structure at applied voltages corresponding to the phonon frequencies. At about 4 meV a maximum is observed in the phonon density of states by analogy to the soft-phonon structure in neutron scattering experiments for LuNi 2 B 2 C ͓P. Dervenagas et al., Phys. Rev. B52, R9839 ͑1995͔͒and YNl 2 B 2 C ͓H. Kawano et al., Czech. J. Phys. 46, S2-825 ͑1996͒, Phys. Rev. Lett. 77, 4628 ͑1996͔͒. In the Ho compound the low-energy phonon peak is suppressed by an applied magnetic field in an anisotropic way, pointing to an interaction between the phonons and the magnetic systems. Surprisingly, in the nonmagnetic Y compound the 4-meV peak is also suppressed by a magnetic field. In the Ho-compound contacts which show the ͗quasi-t...

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Section: ͑Tӎ0͒ ͑2͒mentioning

confidence: 96%

Section: ͑Tӎ0͒ ͑2͒mentioning

confidence: 99%

Section: The Origin Of the Spectral Structurementioning

confidence: 99%

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Point-contact-spectroscopy evidence of quasi-particle interactions in RNi2B2C (R=Ho, Y)

Yanson

Fisun

Jansen

et al. 1997

Low Temperature Physics

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“…When the biasing voltage becomes large enough to increase the local temperature of the junction across the magnetic transition temperature, a distinct non-linearity shows up as a turning point in dV /dI. 53,54 (For the joule heated junction shown in Fig. 4b, this turning point occurs at ∼ 52 mV).…”

Section: Thermal Limit Pcs On Magnetic Compounds Detects the Magnementioning

confidence: 99%

Detection of orbital fluctuations above the structural transition temperature in the iron pnictides and chalcogenides

et al. 2012

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We use point contact spectroscopy (PCS) to probe AEFe2As2 (AE = Ca, Sr, Ba) and Fe1+yTe. For AE = Sr, Ba we detect orbital fluctuations above TS while for AE = Ca these fluctuations start below TS. Co doping preserves the orbital fluctuations while K doping suppresses it. The fluctuations are only seen at those dopings and temperatures where an in-plane resistive anisotropy is known to exist. We predict an in-plane resistive anisotropy of Fe1+yTe above TS. Our data are examined in light of the recent work by W.-C. Lee and P. Phillips (arXiv:1110.5917v2). We also study how joule heating in the PCS junctions impacts the spectra. Spectroscopic information is only obtained from those PCS junctions that are free of heating effects while those PCS junctions that are in the thermal regime display bulk resistivity phenomenon.

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“…Then the temperature in the PC region is locally increased by Joule overheating with the applied voltage increasing [8].…”

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confidence: 99%

Point-Contact Spectroscopy of Ce_1-xRE_xNi₅(RE = Pr, Nd)

et al. 2000

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We report on the study of the electron-quasiparticle interaction function in Ce 1-x RΕx Νi5 (RE = Pr, Nd) pseudobinary compounds for x = 0, 0.2, 0.5, 0.8, and 1 measured by means of point-contact spectroscopy. The measured point-contact spectra (d2V/dI2 -directly proportional to the electron-qnasiparticle interaction function) of the heterocontacts between Ce 1-x REx Ni5 and Cn in the ballistic regime are presented.PACS nnmbers: 73.40. Jn, 71.70.Ch, 71.70.Gm In this paper we present the results in Ce1-xRExΝi5 (RE = Pr, Nd) pseudobinary compounds obtained from point-contact (PC) spectroscopy in order to obtain information on the modification of the electron-quasiparticle interaction (EQI) function. In REΝi 5 compounds the Ni ions are not magnetic and the magnetic properties are determined by RE. CeΝi 5 is a Stoner enhanced paramagnet which is characterized by the influence of spin fluctuations on its properties [1]. On the other hand, PrΝi5 is a Van Vleck paramagnet [2] in which the absence of magnetic order is due to the existence of a singlet nonmagnetic crystalline electric ffeld (CEF) groind state, while NdNi 5 is a ferromagnetic compound (Τ = 8 K [3, 4]) with a doublet CAF ground state.In order to study the disappearance of the spin fluctuation effects in CeΝi5 [1] and the evolution of the CEF energy level scheme in these series we have measured polycrystalline samples of pseudobinary Ce 1 -x REx Hi5 series with x = 0.2, 0.5, and 0.8 by means of point-contact spectroscopy. The compounds Ce 1 -x Prx Ni 5 are all paramagnetic and Ce1-x Νdx Νi5 with x = 0.2, 0.5, and 0.8 are ferromagnetic with TC 2 K, 3.5 K, and 5.1 K, respectively [5].The point-contact spectroscopy has proved to be a very useful experimental method for the direct study of the energy dependence of the interaction between conduction electrons and quasiparticle excitations in metals [6,7]. Small constrictions between two metals show deviations from Ohm's law. For such clean metallic (795)

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Singularities in d2V/dI2 dependences of point contacts between ferromagnetic metals

Cited by 81 publications

References 2 publications

Point-contact-spectroscopy evidence of quasi-particle interactions in RNi2B2C (R=Ho, Y)

Point-contact-spectroscopy evidence of quasi-particle interactions in RNi2B2C (R=Ho, Y)

Detection of orbital fluctuations above the structural transition temperature in the iron pnictides and chalcogenides

Point-Contact Spectroscopy of Ce_1-xRE_xNi₅(RE = Pr, Nd)

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Singularities in d2V/dI2 dependences of point contacts between ferromagnetic metals

Cited by 81 publications

References 2 publications

Point-contact-spectroscopy evidence of quasi-particle interactions in RNi2B2C (R=Ho, Y)

Point-contact-spectroscopy evidence of quasi-particle interactions in RNi2B2C (R=Ho, Y)

Detection of orbital fluctuations above the structural transition temperature in the iron pnictides and chalcogenides

Point-Contact Spectroscopy of Ce1-xRExNi5(RE = Pr, Nd)

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Point-Contact Spectroscopy of Ce_1-xRE_xNi₅(RE = Pr, Nd)