TY - JOUR AU - Jánossy, András AU - Brunel, LC AU - Cooper, Jr TI - Gd3+ ESR determination of the local spin susceptibility in Gd:YBa2Cu3Oy high-temperature superconductors JF - PHYSICAL REVIEW B J2 - PHYS REV B VL - 54 PY - 1996 IS - 14 SP - 10186 EP - 10191 PG - 6 SN - 2469-9950 DO - 10.1103/PhysRevB.54.10186 UR - https://m2.mtmt.hu/api/publication/2609332 ID - 2609332 AB - Gd3+ ESR at high fields in Gd-doped high-T-c superconductors is shown to be a precise probe of the conduction electron static spin susceptibility, chi. The Gd3+ ESR Knight shift at 245 GHz and the spin relaxation broadening at 245 and 9.2 GHz in Gd0.01Y0.99Ba2Cu3Oy (with various values of between 6.05 and 7.0) are in agreement with published Y-89 NMR data above 70 K and provide additional measurements at the rare earth site at much lower temperatures. In the superconducting compounds chi(T) differs strongly from the Yoshida function and at low T it follows a T or T-2 dependence. An anomalous ESR line shape is found at low T in the superconducting state; we provisionally attribute this to a small (10(-2)-10(-3) mu(B)) static magnetic moment on planar Cu sites. LA - English DB - MTMT ER - TY - JOUR AU - Rockenbauer, Antal AU - Jánossy, András AU - Korecz, László AU - Pekker, Sándor TI - Electron paramagnetic resonance spectroscopy of Gd-doped YBa2CU3O6+y crystallites aligned in a magnetic field JF - JOURNAL OF MAGNETIC RESONANCE J2 - J MAGN RESON VL - 97 PY - 1992 IS - 3 SP - 540 EP - 552 PG - 13 SN - 1090-7807 DO - 10.1016/0022-2364(92)90034-5 UR - https://m2.mtmt.hu/api/publication/2538786 ID - 2538786 AB - Gd EPR spectra of Y0.999Gd0.001Ba2Cu3O6+y (0 ≤ y ≤ 1.) crystallites aligned in a magnetic field are investigated with field parallel to the c crystalline axis. For low oxygen contents (y ≤ 0.1) no spectral change is observed, while for larger oxygen contents all major bands except the central peak split into a pattern of five subbands with y-dependent relative intensities. The five sets of subbands are assigned to oxygen configurations with zero, one, two, three, or four occupied positions in the Cu (1) Oy planes closest to the Gd atom. The spectroscopic parameters g, h2 0, b4 0, b6 0, b4 4, and b6 4 determined by an iteration procedure reconstruct well the positions of all allowed and forbidden transitions. Each subsequent oxygen coordination increases b2 2 by the same amount; this shows that the zero-field splitting depends linearly on the crystal field. © 1992. LA - English DB - MTMT ER - TY - JOUR AU - Pekker, Sándor AU - Jánossy, András AU - Rockenbauer, Antal TI - Ordering of oxygen into chains and distribution of hole density in YBa2Cu3O1+x JF - PHYSICA C - SUPERCONDUCTIVITY AND ITS APPLICATIONS J2 - PHYSICA C VL - 181 PY - 1991 IS - 1-3 SP - 11 EP - 17 PG - 7 SN - 0921-4534 DO - 10.1016/0921-4534(91)90328-V UR - https://m2.mtmt.hu/api/publication/1478442 ID - 1478442 AB - A series of Y0.999Gd0.001Ba2Cu3O6+x compounds is studied by Gd3+ EPR in the full range of oxygen content. The fine structu re is modified by the hole distribution in the Cu(2)O2 layers mirroring oxygen chains in the Cu(1)Ox layers. The fine structure of 5 differently occupied first-neighbour Cu(1)Ox oxygen chain configurations surrounding the Gd3+ ions is resolved. Formation of chain begins at a threshold oxygen content x0=0.14. For x>0.14 oxygen in Cu(1)Ox planes is ordered mainly into chains, the amount of disordered oxygen decreases with increasing x. The EPR intensities are in quantitative agreement with a model calculation of 2-dimensionally ordered oxygen chains. © 1991. LA - English DB - MTMT ER - TY - JOUR AU - Jánossy, András AU - Rockenbauer, Antal AU - Pekker, Sándor TI - Gd3+ electron paramagnetic resonance in the quasi-two-dimensional antiferromagnet YBa2Cu3O6.02:Gd JF - PHYSICA C - SUPERCONDUCTIVITY AND ITS APPLICATIONS J2 - PHYSICA C VL - 167 PY - 1990 IS - 3-4 SP - 301 EP - 306 PG - 6 SN - 0921-4534 DO - 10.1016/0921-4534(90)90346-G UR - https://m2.mtmt.hu/api/publication/1478444 ID - 1478444 AB - Electron paramagnetic resonance (EPR) at 9.25 GHz of Y1-xGdxBa2Cu3O6.02 (0.001 < x < 0.05) powder magnetically a ligned along the crystallographic c-direction shows a well resolved Gd3+ fine structure. The crystalline field parameters are determined and their temperature dependence discussed. Due to the special symmetry the exchange interaction between Gd3+ and antiferromagnetic CuO2 layers is small, contrary to Y2-uGduBaCuO5 where Gd3+ and Cu2+ magnetizations are strongly coupled. EPP serves as a probe for internal fields HI at the Gd sites; in Y0.99Gd0.01Ba2Cu2.97Fe0.03O6.02HI<15 G despite the Fe-induced magnetic transition. © 1990. LA - English DB - MTMT ER -