Publications (50)
Peculiarities of the superconducting gaps and the electron-boson interaction in TmNi2B2C as seen by point-contact spectroscopy
Yu. G. Naidyuk, O. E. Kvitnitskaya, L. V. Tiutrina +6
Point-contact (PC) investigations on the title compound in the normal and superconducting (SC) state (Tc=10,6 K) are presented. The temperature dependence of the SC gap of TmNi2B2C…
Infrared photo-response of Fe-shunted Ba-122 thin film microstructures
L. Rehm, D. Henrich, M. Hofherr +10
We present a study of the response to pulsed infrared radiation of Fe-layer shunted pnictide thin film microstructures. The thin film multilayer consisting of 20 nm thick Fe-buffer…
Strain induced superconductivity in the parent compound BaFe2As2
J. Engelmann, V. Grinenko, P. Chekhonin +10
The discovery of superconductivity (SC) with a transition temperature, Tc, up to 65K in single-layer FeSe (bulk Tc =8K) films grown on SrTiO3 substrates has attracted special atten…
Current-induced conductance switching in epitaxial La0.7Sr0.3MnO3/SrTiO3 multilayers
K. Doerr, K. -H. Mueller, T. Walter +6
We report on the non-linear in-plane electrical transport in coherently grown [La0.7Sr0.3MnO3/SrTiO3] multilayers with ultrathin (< 3 nm) single layers. Current-induced switching o…
Point-contact study of the LuNi2B2C borocarbide superconducting film
O. E. Kvitnitskaya, Yu. G. Naidyuk, I. K. Yanson +4
We present point-contact (PC) Andreev-reflection measurements of a superconducting epitaxial c-axis oriented nickel borocarbide film LuNi2B2C (Tc=15.9 K). The averaged value of the…
Quantitative assessment of pinning forces and the superconducting gap in NbN thin films from complementary magnetic force microscopy and transport measurements
T. Shapoval, H. Stopfel, S. Haindl +5
Epitaxial niobium-nitride thin films with a critical temperature of Tc=16K and a thickness of 100nm were fabricated on MgO(100) substrates by pulsed laser deposition. Low-temperatu…
Influence of strain on magnetization and magnetoelectric effect in La0.7A0.3MnO3 / PMN-PT(001) (A = Sr; Ca)
C. Thiele, K. Dorr, O. Bilani +2
We investigate the influence of a well-defined reversible biaxial strain <=0.12 % on the magnetization (M) of epitaxial ferromagnetic manganite films. M has been recorded depending…
Highly anisotropic energy gap in superconducting Ba(FeCo)As from optical conductivity measurements
T. Fischer, A. V. Pronin, J. Wosnitza +6
We have measured the complex dynamical conductivity, , of superconducting Ba(FeCo)As ( K) at terahertz frequencies and…
Direct observation of superconducting vortex clusters pinned by a periodic array of magnetic dots in ferromagnetic/superconducting hybrid structures
T. Shapoval, V. Metlushko, M. Wolf +3
Strong pinning of superconducting flux quanta by a square array of 1 m-sized ferromagnetic dots in a magnetic-vortex state was visualized by low-temperature magnetic force micr…
Texture and morphology of epitaxially grown LuNi2B2C thin films on single crystalline MgO substrates of different orientation
T. Niemeier, R. Huhne, L. Schultz +1
This paper has been withdrawn and will be replaced as soon as possible.
The role of carbon for superconductivity in MgCNi from specific heat
A. Wälte, G. Fuchs, K. -H. Müller +3
The influence of carbon deficiency on superconductivity of MgCNi is investigated by specific heat measurements in the normal and superconducting state. In order to perform a…
Point-contact spectroscopy of the nickel borocarbide superconductor YNi2B2C in the normal and superconducting state
D. L. Bashlakov, Yu. G. Naidyuk, I. K. Yanson +5
Point-contact (PC) spectroscopy measurements of YNi2B2C single crystals in the normal and superconducting (SC) state (T_c=15.4K) for the main crystallographic directions are report…
Observation of minority spin character of the new electron doped manganite La_0.7Ce_0.3MnO_3 from tunneling magnetoresistance
C. Mitra, P. Raychaudhuri, K. Doerr +4
We report the magnetotransport characteristics of a trilayer ferromagnetic tunnel junction build of an electron doped manganite (La_0.7Ce_0.3MnO_3) and a hole doped manganite (La_0…
Lattice structure and magnetization of LaCoO3 thin films
A. D. Rata, A. Herklotz, L. Schultz +1
We investigate the structure and magnetic properties of thin films of the LaCoO compound. Thin films are deposited by pulsed laser deposition on various substrates in order t…
Adaptive modulations of martensites
S. Kaufmann, U. K. Roessler, O. Heczko +4
Modulated phases occur in numerous functional materials like giant ferroelectrics and magnetic shape memory alloys. To understand the origin of these phases, we review and generali…
Tuning of crystal structure and magnetic properties by exceptionally large epitaxial strains
J. Buschbeck, I. Opahle, M. Richter +7
Huge deformations of the crystal lattice can be achieved in materials with inherent structural instability by epitaxial straining. By coherent growth on seven different substrates…
Strong Tc dependence for strained, epitaxial Ba(Fe1-xCox)2As2 thin films
K. Iida, J. Haenisch, R. Huehne +6
Ba(Fe1-xCox)2As2 superconducting thin films have been grown on SrTiO3, (La,Sr)(Al,Ta)O3, LaAlO3 and YAlO3 (YAO) single crystal substrates by pulsed laser deposition. All the films,…
Upper critical field and irreversibility line in superconducting MgB_2
G. Fuchs, K. -H. Müller, A. Handstein +5
The upper critical field Hc2(T) of sintered pellets of the recently discovered MgB_2 superconductor was investigated by transport, ac susceptibility and dc magnetization measuremen…
Growth and characterization of epitaxial LuNi2B2C thin films on MgO single crystals
T. Niemeier, R. Hühne, A. Köhler +3
Biaxially textured LuNi2BC thin films with Tc up to 15.8 K and a residual resistivity ratio up to 15 have been prepared. The films were deposited on MgO(110) substrates using pulse…
Evidence for Kondo Effect in Au80Co20 Ribbons
D. S. Geoghegan, A. Huetten, K. -H. Mueller +1
A minimum in resistivity as a function of temperature for an as-quenched Au80Co20 ribbon prepared by melt-spinning using a wheel surface speed of 20 m s^{-1} is found at 25 K. No r…
Electronic phase diagram of disordered Co doped BaFe2As2
F. Kurth, K. Iida, S. Trommler +8
Superconducting and normal state transport properties in iron pnictides are sensitive to disorder and impurity scattering. By investigation of Ba(Fe1-xCox)2As2 thin films with vary…
Direct observation of a nodeless superconducting energy gap in the optical conductivity of iron-pnictides
B. Gorshunov, D. Wu, A. A. Voronkov +7
The temperature-dependent optical reflectivity and complex transmissivity of an epitaxially grown Ba(FeCo)As thin film were measured and the optical conduct…
Competing magnetic interactions in exchange bias modulated films
C. Hamann, B. P. Toperverg, K. Theis-Bröhl +5
The magnetization reversal in stripe-like exchange bias patterned thin films was investigated by complementary inductive and high resolution magneto optic…
Scaling behaviour of the critical current in clean epitaxial Ba(Fe1-xCox)2As2 thin films
K. Iida, J. Haenisch, T. Thersleff +6
The angular-dependent critical current density, Jc(theta), and the upper critical field, Hc2(theta), of epitaxial Ba(Fe1-xCox)2As2 thin films have been investigated. No Jc(theta) p…
A 'p-n' diode with hole and electron-doped lanthanum manganite
C. Mitra, P. Raychaudhuri, G. Kobernik +4
The hole-doped manganite La0.7Ca0.3MnO3 and the electron-doped manganite La0.7Ce0.3MnO3 undergo an insulator to metal transition at around 250 K, above which both behave as a polar…
Epitaxial LaFeAsOF thin films grown by pulsed laser deposition
M. Kidszun, S. Haindl, E. Reich +3
Superconducting and epitaxially grown LaFeAsOF thin films were successfully prepared on (001)-oriented LaAlO3 substrates using pulsed laser deposition. The prepared thin films show…
MgCNi3 : Complex behavior in a strongly coupled superconductor
A. Waelte, H. Rosner, M. D. Johannes +8
Polycrystalline samples of the recently discovered MgCNi3 superconductor were investigated by transport, ac susceptibility, dc magnetization and specific heat measurements in magne…
Evidence for Pauli-limiting behaviour at high fields and enhanced upper critical fields near T_c in several disordered FeAs based Superconductors
G. Fuchs, S. -L. Drechsler, N. Kozlova +11
We report resistivity and upper critical field B_c2(T) data for disordered (As deficient) LaO_0.9F_0.1FeAs_1-delta in a wide temperature and high field range up to 60 T. These samp…
Pair weakening in mixed rare-earth nickel borocarbides (R,R')Ni2B2C
J. Freudenberger, K. -H. Mueller, G. Fuchs +3
In this study pseudoquaternary rare-earth nickel borocarbide superconductors RxR'1-xNi2B2C have been investigated predominantly in the diluted limit x << 1 or (1 x) << 1. In all of…
Epitaxial growth and anisotropy of La(O,F)FeAs thin films deposited by Pulsed Laser Deposition
E. Backen, S. Haindl, T. Niemeier +5
LaFeAsO1-xFx thin films were deposited successfully on (001)-oriented LaAlO3 and MgO substrates from stoichiometric LaFeAsO1-xFx polycrystalline targets with fluorine concentration…
Comparative Study of Dense Bulk MgB Materials Prepared by Different Methods
V. N. Narozhnyi, G. Fuchs, A. Handstein +10
We report on the results of a comparative investigation of highly dense bulk MgB samples prepared by three methods: (i) hot deformation; (ii) high pressure sintering; and (iii)…
The Effect of 45° Grain Boundaries and associated Fe particles on Jc and resistivity in Ba(Fe0.9Co0.1)2As2 Thin Films
J. Hänisch, K. Iida, F. Kurth +6
The anisotropy of the critical current density Jc depends in general on both the properties of the flux lines (such as line tension, coherence length and penetration depth) and the…
Magnetic-field induced band-structure change in CeBiPt
N. Kozlova, J. Hagel, M. Doerr +11
We report on a field-induced change of the electronic band structure of CeBiPt as evidenced by electrical-transport measurements in pulsed magnetic fields. Above ~25 T, the charge-…
High-Field Pauli-Limiting Behavior and Strongly Enhanced Upper Critical Magnetic Fields near the Transition Temperature of an Arsenic-Deficient LaO_0.9F_0.1FeAs_(1-δ) Superconductor
G. Fuchs, S. -L. Drechsler, N. Kozlova +14
We report upper critical field B_c2(T) data for disordered (arsenic-deficient) LaO_0.9F_0.1FeAs_(1-delta) in a wide temperature and magnetic field range up to 47 T. Because of the…
Superconducting Bulk Magnets: Very High Trapped Fields and Cracking
S. Gruss, G. Fuchs, G. Krabbes +5
Improved trapped fields are reported for bulk melt-textured YBa2Cu3O7-x (YBCO) material in the temperature range between 20 K and 50 K. Trapped fields up to 12.2 T were obtained at…
Weak inter-band coupling in MgB: a specific heat analysis
A. Wälte, S. -L. Drechsler, G. Fuchs +4
The superconducting state of MgB is investigated by specific heat measurements in detail. The specific heat in the normal state is analyzed using a recently developed…
Strain-induced insulator state in La_0.7Sr_0.3CoO_3
A. D. Rata, A. Herklotz, K. Nenkov +2
We report on the observation of a strain-induced insulator state in ferromagnetic La_0.7Sr_0.3CoO_3 films. Tensile strain above 1% is found to enhance the resistivity by several or…
Fully dense MgB_2 superconductor textured by hot deformation
A. Handstein, D. Hinz, G. Fuchs +5
Bulk textured MgB_2 material of nearly full density showing a weak c-axis alignment of the hexagonal MgB_2 grains parallel to the pressure direction was obtained by hot deformation…
Upper critical field measurements up to 60 T in arsenic-deficient LaO_(0.9)F_(0.1)FeAs_(1-delta): Pauli limiting behaviour at high fields vs improved superconductivity at low fields
G. Fuchs, S. -L. Drechsler, N. Kozlova +7
We report resistivity and upper critical field B_c2(T) data for As deficient LaO_(0.9)F_(0.1)FeAs_(1-delta) in a wide temperature and high field range up to 60 T. These disordered…
Improved superconducting properties in nanocrystalline bulk MgB_2
A. Gümbel, J. Eckert, G. Fuchs +3
Highly dense nanocrystalline MgB_2 bulk superconductors with distinctly improved pinning were prepared by mechanical alloying of Mg and B powders and hot compaction at ambient temp…
Evidence for strong electron-phonon coupling in MgCNi_3
A. Waelte, G. Fuchs, K. -H. Mueller +7
The title compound is investigated by specific heat measurements in the normal and superconducting state supplemented by upper critical field transport, susceptibility and magnetiz…
Anisotropy of iron-platinum-arsenide Ca10(PtnAs8)(Fe2-xPtxAs2)5 single crystals
F. F. Yuan, Y. Sun, W. Zhou +7
The upper critical field Hc2 anisotropy of Ca10(PtnAs8)(Fe2-xPtxAs2)5 (n = 3, 4) single crystals with long FeAs interlayer distance (d) was studied by angular dependent resistivity…
Reversible strain effect on the magnetization of LaCoO3 films
A. Herklotz, A. D. Rata, L. Schultz +1
The magnetization of ferromagnetic LaCoO3 films grown epitaxially on piezoelectric substrates has been found to systematically decrease with the reduction of tensile strain. The ma…
Orbital and spin effects for the upper critical field in As deficient disordered Fe pnictide superconductors
G. Fuchs, S. -L. Drechsler, N. Kozlova +17
We report B_c2 data for LaO_{0.9}F_{0.1}FeAs_{1-delta} in a wide T and field range up to 60 Tesla. The large slope of B_c2 approx ~ -6 Tesla/K near an improved T_c = 28.5 K of the…
Unusually high critical current of clean P-doped BaFe2As2 single crystalline thin film
F. Kurth, C. Tarantini, V. Grinenko +12
Microstructura lly clean, isov alently P-doped BaFe2As2 (Ba-122) single crystalline thin films have been prepared on MgO (001) substrates by molecular beam epitaxy. These films sho…
Critical current scaling and anisotropy in oxypnictide superconductors
M. Kidszun, S. Haindl, T. Thersleff +6
Investigating the anisotropy of superconductors permits an access to fundamental properties. Having succeeded in the fabrication of epitaxial superconducting LaFeAs(O,F) thin films…
Monopolelike probes for quantitative magnetic force microscopy: calibration and application
S. Vock, F. Wolny, T. Mühl +6
A local magnetization measurement was performed with a Magnetic Force Microscope (MFM) to determine magnetization in domains of an exchange coupled [Co/Pt]/Co/Ru multilayer with pr…
Influenced of Fe buffer thickness on the crystalline quality and the transport properties of Fe/Ba(Fe1-xCox)2As2 bilayers
K. Iida, S. Haindl, T. Thersleff +8
The implementation of an Fe buffer layer is a promising way to obtain epitaxial growth of Co-doped BaFe2As2 (Ba-122). However, the crystalline quality and the superconducting prope…
Point-contact study of ReFeAs(1-x)Fx (Re=La, Sm) superconducting films
Yu. G. Naidyuk, O. E. Kvitnitskaya, I. K. Yanson +5
Point-contact (PC) Andreev-reflection (AR) measurements of the superconducting gap in iron-oxipnictide ReFeAsO_{1-x}F_x (Re=La, Sm) films have been carried out. The value of the ga…
LaFeAsOF thin films: high upper critical fields and evidence of weak link behavior
S. Haindl, M. Kidszun, A. Kauffmann +9
High-quality superconducting LaFeAsOF thin films were grown on single crystalline LaAlO substrates with critical temperatures (onset) up to 28 K. Resistive meas…