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Browsing by Author "Keller H."

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Clues Obtained from the Oxygen Isotope Effect on NMR/NQR Parameters Observed in YBa2Cu4O8

Mali M.; Roos J.; Keller H.; Dooglav A.; Sakhratov Y.; Savinkov A. (2002)

Nuclear magnetic and nuclear quadrupole resonance (NMR, NQR) techniques have a precision allowing one to determine rather small isotope effects. Well-defined oxygen stoichiometry and negligible oxygen diffusion makes ...
Debye temperature in YBa2Cu3Ox as measured from the electron spin-lattice relaxation of doped Yb3+ ions

Aminov L.; Ivanshin V.; Kurkin I.; Gafurov M.; Salikhov I.; Keller H.; Gutmann M. (2001)

The electron spin-lattice relaxation (SLR) times T1 of Yb3+ ions were measured from the temperature dependence of electron spin resonance line width in Y0.99Yb0.01Ba2Cu3Ox with different oxygen contents. Raman relaxation ...
Electron paramagnetic resonance of Tb 3+ ions in YBa 2Cu 3O 6

Gafurov M.; Ivanshin V.; Kurkin I.; Rodionova M.; Keller H.; Gutmann M.; Staub U. (2000)

The first observation of electron paramagnetic resonance (EPR) of Tb 3+ doped into YBa 2 Cu 3O 6 is reported. EPR is used to determine the local symmetry of the rare-earth ion and to study the effect of suppression of ...
Electron spin resonance with geff ≈ 4.2 in YBa2Cu3O6.35. model of chain copper-oxygen fragments

Eremin M.; Eremina R.; Gafurov M.; Ivan'shin V.; Kurkin I.; Kurzin S.; Keller H.; Gutmann M. (2000)

Systematic measurements are made of ESR spectra with g ≈ 4.2 in YBa2Cu3O6+y compounds with various doping indices y. Temperature dependences of the spectrum intensity show that the ground states of the centers are singlet ...
Electron spin-lattice relaxation of Er3+-ions in Y0.99Er0.01Ba2Cu3Ox

Ivanshin V.; Gafurov M.; Kurkin I.; Kurzin S.; Shengelaya A.; Keller H.; Gutmann M. (1998)

The temperature dependence of the electron spin-lattice relaxation (SLR) was studied in Y0.99Er0.01Ba2Cu3Ox(0 ≤ x ≤ 7). The data derived from the electron spin resonance (ESR) and SLR measurements were compared to those ...
Electronic phase separation and unusual isotope effects in La2-x Sr x CuO4 observed by electron paramagnetic resonance

Shengelaya A.; Kochelaev B.; Conder K.; Keller H. (2007)

We review the results of our recent studies of La2-x Sr x CuO4 cuprate superconductor using electron paramagnetic resonance (EPR). It is shown that the EPR of Mn2+ doped into La 2-x Sr x CuO4 (LSCO) provides an unique ...
EPR in La1-xCaxMnO3: Relaxation and bottleneck

Shengelaya A.; Zhao G.; Keller H.; Müller K.; Kochelaev B. (2000)

Recent EPR and susceptibility measurements in La1-xCaxMnO3 support the existence of a bottleneck EPR regime up to 1000 K quantitatively. The EPR linewidth and electrical conductivity follow the same temperature dependence ...
EPR of YBa2Cu3O6+y: Models of paramagnetic centers with g ≈ 4.2

Eremina R.; Eremin M.; Gafurov M.; Ivanshin V.; Kurkin I.; Kurzin S.; Keller H.; Gutmann M. (2000)

A systematic investigation of the EPR line with g ≈ 4.2 in YBa2Cu3O6+y has been carried out. From the temperature dependence of the line integrated intensity we have deduced that the line is due to paramagnetic centers ...
EPR study of some rare-earth ions (Dy3+, Tb3+, and Nd3+) in YBa2Cu3O6-compound

Gafurov M.; Ivanshin V.; Kurkin I.; Rodionova M.; Keller H.; Gutmann M.; Staub U. (2003)

We investigate the low temperature X-band electron paramagnetic resonance (EPR) of YBa2Cu3Ox compounds with x≅6.0 doped with Dy3+, Tb3+, and Nd3. The EPR spectra of Dy3+ and Tb3+ have been identified. The EPR of Tb3+ is ...
EPR study on higher oxygen pressure synthesized compound Pr2-xGdxCuO4

Ivanshin V.; Mamin G.; Shengelaya A.; Keller H.; Klamut P.; Sikora A. (1999)

The electron paramagnetic resonance (EPR) and magnetic susceptibility measurements were performed in Pr2-xGdxCuO4 (x = 0.02; 0.05) annealed at the higher oxygen pressures of 15 and 21 bar. This annealing treatment causes ...
Inhomogeneous broadening of the EPR signal of Yb3+ ions in domain walls of lightly doped antiferromagnetic cuprates

Vishina A.; Maisuradze A.; Shengelaya A.; Kochelaev B.; Keller H. (2012)

Distortion of the long-range antiferromagnetic order in the YBa2Cu3O6+y is investigated by the electron paramagnetic resonance (EPR) measurements for y = 0.1 - 0.4. In the case of the doping level y = 0.2, 0.3 the EPR ...
Microwave studies of the superconducting state in Rb3C60

Ivanshin V.; Schauwecker R.; Warden M.; Erhart P.; Keller H.; Guentherodt H.; Lang H.; Thommen-Geiser V. (1996)

Methods of electron-spin resonance (ESR) and direct, non-linear field-modulated microwave absorption (FMMA) were applied for the measurements in low-and high-purity samples of rubidium-doped fullerene, Rb3C60. The coexistence ...
Probing the Yb3+ spin relaxation in Y0.98 Yb0.02 Ba2 Cu3 Ox by electron paramagnetic resonance

Maisuradze A.; Shengelaya A.; Kochelaev B.; Pomjakushina E.; Conder K.; Keller H.; Müller K. (2009)

The relaxation of Yb3+ in YBa2 Cu3 Ox (6<x<7) was studied using electron paramagnetic resonance. It was found that both electronic and phononic processes contribute to the Yb3+ relaxation. The phononic part of the relaxation ...
Spin excitations and electron paramagnetic resonance in two-layer antiferromagnetic system Y1-xYbxBa2Cu 3O6+y

Vishina A.; Maisuradze A.; Shengelaya A.; Kochelaev B.; Keller H. (2012)

An experimental and theoretical study of the EPR spectrum of Y 0.98Yb0.02Ba2Cu3O6.1 is reported. A strong anisotropy of the EPR linewidth is revealed for the parallel and perpendicular orientations of the external magnetic ...
Spontaneous ferromagnetic spin ordering at the surface of La2 Cu O4

Yusupov R.; Kabanov V.; Mihailovic D.; Conder K.; Müller K.; Keller H. (2007)

Magnetic properties of high purity stoichiometric La2 Cu O4 nanoparticles are systematically investigated as a function of particle size. Ferromagnetic single-domain spin clusters are shown to spontaneously form at the ...
The oxygen isotope effect on the infrared photo-induced absorption spectra of La 2CuO 4

Yusupov R.; Conder K.; Mertelj T.; Mihailovic D.; Müller K.; Keller H. (2006)

The infrared photo-induced spectra of the isotope-substituted stoichiometric La 2CuO 4 samples were studied at T=20 K. Measured spectra were analyzed within the small polaron hopping theory. A small, but detectable shift ...
Three-spin-polarons and their elastic interaction in cuprates

Kochelaev B.; Safina A.; Shengelaya A.; Keller H.; Müller K.; Conder K. (2003)

Properties of quasiparticles in doped cuprates formed by an oxygen hole and two adjacent copper holes are investigated on the basis of the extended Hubbard model. The ground state energy, wave functions and the polaron-phonon ...
Tilting mode relaxation and oxygen isotope effect in La 2-xSrxCuO4 studied by electron paramagnetic resonance

Shengelaya A.; Keller H.; Müller K.; Kochelaev B.; Conder K. (2000)

The electron paramegnetic resonance (EPR) of Mn2+ doped into La2-xSrxCuO4 was used to probe the copper spin relaxation via the bottleneck effect for oxygen isotope (16O and 18O)-substituted samples. It was found that the ...

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Browsing by Author "Keller H."

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