Local triplet superconductivity ofLa0.65Ca0.35MnO3−Xpoint contacts

V. N. Krivoruchko

¹

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V. Yu. Tarenkov

²

Induced triplet pairing in cleans-wave superconductor/ferromagnet layered structures

“…Superconducting characteristics, such as a critical temperature and enhanced sub-gap conductance, have been observed in point contact conductance measurements on s-wave superconductor/half metallic systems. 15 Perhaps most compelling is the observation of a Josephson current through a strong almost half-metallic, ferromagnet. 16 All of these experiments indicate long range superconducting correlations that are not destroyed by a strong exchange field: a triplet state would obviously be consistent with these experiments.…”

Point-contact Andreev-reflection spectroscopy of doped manganites: Charge carrier spin-polarization and proximity effects (Review Article)

“…Contribution of such a small region to the contact's resistance is less than 1%. That is indeed observed for the most part of the samples [15,[22][23][24][25][26][27][28][29][49][50][51][52][53][54][55]. However, for some of the cases, the measured contact's spectra revealed very distinct features which were interpreted as manifestation of an unconventional proximity effect.…”

“…For the first time direct experimental evidence of half-metallic density of states in ferromagnetic La 0.7 Ca 0.3 MnO 3 was obtained by scanning tunneling spectroscopy by Wei et al [44]. These results were then confirmed by optical [5,[45][46][47][48] and transport measurements [15,[22][23][24][25][26][27][28][29][49][50][51][52][53][54][55]. However, it should be taken into account that different experiments yield quite different value of spin polarization (see Table 1).…”

“…If the contact's size is not small, d > ξ S , the PE can be important. For proximity affected contacts, it was suggested [25,26,28,29] that the conditions for an unconventional PE are fulfilled. Indeed, the main condition for spin triplet pairing to be induced at sSC/F interface is the "spin active" interface, i.e., the ability of the sSC/F interface to convert a singlet pair into a triplet one.…”

“…Since then, this technique has been used to measure spin polarization in a broad range of ferromagnetic materials, including the transition metal elements Fe, Ni, and Co [15,17], metallic alloys of transition metals such as permalloy [15,18], Heusler alloys such as NiMnSb [15,19], halfmetals such as CrO 2 [15,[19][20][21], doped manganites [15,19,[22][23][24][25][26][27][28][29], and other ferromagnetic metals and semiconductors. The foregoing may lead to a conclusion that the PCAR technique is indeed a robust and universal way for measuring spin polarization applicable to all magnetic compounds.…”