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Last modified
01.02.2019
|
Andreev-reflection
and PC spectroscopy of modern superconductors Staff:
| Bashlakov D.L. |
bashlakov at ilt.kharkov.ua
|
| Bobrov
N.L. |
bobrov at ilt.kharkov.ua
|
| Gamayunova
N.V. |
gamayunova at ilt.kharkov.ua
|
| Kvitnitskaya О.Е.
|
kvitnitskaya at ilt.kharkov.ua |
|
Naidyuk Yu.G. |
naidyuk
at
ilt.kharkov.ua
|
|
Tiutrina L.V.
|
tiutrina at ilt.kharkov.ua |
Main research:
-
investigation
of modern superconductors
— rare-earth nickelborocarbides, magnesium diboride, high-temperature and
iron-based superconductors by Andreev reflection spectroscopy;
-
obtaining of
point-contact
spectra of electron-quasiparticle
interaction for
above
mentioned materials;
-
investigation
of coexistence of superconductivity, magnetic ordering and spin/charge
density waves in new high-temperature superconducting
compounds.
Main recent results:
 The data on the
distribution of
superconducting
gap
in new
superconductor
MgB2
with the critical
temperature
of
39 К
were obtained. The presence of two
gaps in
MgB2
is established. Their values
are found to be
2,45±0,15
and
7,0±0.4
mV with the relation
1:3, what is
in
accordance with the theoretical
estimations.
The existence
of two
superconducting
gaps
in
non-magnetic
R=Y,
Lu
and
antiferromagnetic (АFМ)
R=Tm,
Er
nickel-borocarbide
superconducting
compounds
RNi2B2C
was shown.
The
superconducting
gap for
compounds with
commensurate АFM
order
R=Ho
and
Dy
has
a BCS-like
behavior
in
the
antiferromagnetic state. The
gap for
R=Tm
starts to
decrease
at the approach to
the
magnetic
state with non-commensurate АFМ
order.
The existence of
two-band
superconducting state for
antiferromagnetic (TN=6K)
nickel-borocarbide superconductor
(Tc
=11.3K)
ErNi2B2C
is shown.
Such state
is characterized
by two order-parameters.
The
temperature dependence
of
order
parameter
along two main
crystallographic
directions was obtained.
The essential
decrease of
superconducting
order
parameter at the
transition
in
the
antiferromagnetic state was
revealed.
Using
point-contact Andreev-reflection spectroscopy, emergent iron-based pnictide and
chalcogenide superconductors of different structure have been
investigated. Along with determination of superconducting gap and its
temperature and magnetic field dependence suggestions was made how to separate
the spectroscopic features in dV/dI(V) from those caused by the thermal regime.
Using Yanson point-contact spectroscopy single 20 meV boson mode in KFe2As2
was detected. A rise in the superconducting critical temperature Tc of more than
two times (exceeding 20 K) is discovered in point contacts created between iron
chalcogenide FeSe single crystals and Cu.
Equipment:
The point-contact spectrometers for investigation
of nonlinear conductivity of point contacts. The spectrometers have a cryogenic
equipment for creation of point contacts and measuring of
conducting properties of
point contacts
in temperature
interval 1.5-77 K
and magnetic field 0-9T.
International
collaboration:
-
Institute of Experimental Physics,
Kosice, Slovak Republik
-
Leibniz Institute for Solid State and Materials Research, Dresden, Germany
-
Physical Institute
University of Karlsruhe, Karlsruhe, Germany
-
Texas A&M University, College Station, USA
Recent publications
and reviews:
-
Yu. G. Naidyuk,
O. E. Kvitnitskaya, N. V. Gamayunova
D.
L. Bashlakov,
L. V. Tyutrina,
G. Fuchs,
R. Hühne, D. A. Chareev,
and A. N. Vasiliev,
Superconducting gaps in FeSe
studied by soft point-contact Andreev reflection spectroscopy,
Phys.
Rev. B 96, 094517 (2017)
-
Yu.G. Naidyuk, G. Fuchs, D.A. Chareev, A.N. Vasiliev,
Doubling of the critical temperature of FeSe observed in
point contacts,
Phys.
Rev. B 93,
144515 (2016).
-
Yu. G.
Naidyuk, O.E. Kvitnitskaya, S. Aswartham, G. Fuchs, K. Nenkov, and S.
Wurmehl, Exploring point-contact spectra of Ba1−xNaxFe2As2
in the normal and superconducting states,
Phys. Rev. B 89,
104512
(2014).
-
Yu. G.
Naidyuk, O.E. Kvitnitskaya, L. V. Tiutrina, I.K.Yanson, G. Behr, G. Fuchs,
S.-L. Drechsler, K. Nenkov, and L. Schultz, Peculiarities of the
superconducting gaps and the electron-boson interaction in TmNi2B2C
as seen by point-contact spectroscopy,
Phys.
Rev. B, 2011, Vol. 84, p.094516.
-
Yu. G. Naidyuk, O.E. Kvitnitskaya, I.K.Yanson, G Fuchs, S Haindl, M Kidszun, L
Schultz. and B.Holzapfel, Point-contact study of ReFeAsO1-xFx (Re = La, Sm) superconducting films,
Superconductor Science and Technology.
2011,
Vol.24,
p.
065010.
-
N. L. Bobrov, V. N. Chernobay,
Yu. G. Naidyuk, L. V. Tyutrina, D. G. Naugle, K. D. D. Rathnayaka, S. L.
Bud’ko, P. C. Canfield, I. K. Yanson,
Compe-tition
of multiband superconducting and magnetic order in ErNi2B2C
observed by Andreev reflection
Europhys. Lett. 2008,
Vol. 83, p. 37003.
-
Yu.
G.
Naidyuk,
O.
E.
Kvitnitskaya,
I.
K.
Yanson, G. Fuchs, K. Nenkov, A. Waelte, G. Behr, D. Souptel, and S.-L.
Drechsler, Point-contact spectroscopy of the
antiferromagnetic superconductor HoNi2B2C
in the normal and superconducting state,
Phys.
Rev. B, 2007, Vol. 76, p.014520.
-
D. L. Bashlakov, Yu. G.
Naidyuk, I. K. Yanson, G. Behr, S.L. Drechsler, G. Fuchs, L. Schultz and D.
Souptel,
Point-contact spectroscopy of the nickel borocarbide superconductor YNi2B2C
in the normal and superconducting state, J.
Low Temp. Physics, 2007, Vol.147, p.335.
-
I.K. Yanson, Yu.G. Naidyuk,
Advances in point-contact spectroscopy: two-band
superconductor MgB2
(review),
Low Temp.Phys., 2004, Vol.30, p.261.
-
Yu.G. Naidyuk, I.K. Yanson, Point-contact
spectroscopy of the heavy-fermion systems (review).
J. Phys. Condens.
Matter, 1998, Vol.10, p.8905.
-
I.K.Yanson, Contact
spectroscopy of high-temperature superconductors (Review article). Part
I: Physical and methodical fundamentals of contact spectroscopy of high-Tc
superconductors. Experimental results for La2-xSrxCuO4 and their
discussion. Sov.J.Low Temp.Phys., 1991, Vol.17, p.275.
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