Magnetic ordering in single crystals of

Abstract

Heat capacity measurements on pure but twinned single crystals of reveal a sharp peak at , which according to thermal expansion, neutron diffraction, and magnetic susceptibility measurements originates from an antiferromagnetic ordering of the Pr-ion moments. A modest coupling to the Cu(2) spin system is observed. Below a first-order transition in the magnetic structure of the Pr spin system (at 13.4 K in warming; in cooling) is found. Field-dependent heat capacity data show anisotropic temperature dependences of the -peaks and recover a Schottky-like anomaly due to the crystal-field-split ground state of the .

Praseodymium and oxygen role on magnetic properties of PrBa 2 Cu 3 O 6+ x

“…An anomaly around 13 K should be detected for x = 0.9, as it has been previously observed for x = 1 in polycrystals [3] and by neutron diffraction experiment on single crystals [15,16],but in our sample, this temperature is too close to T N (14.5 K) to be well distinguished by this procedure. The fact that it is clearly seen on our x = 0.4 (Fig.…”

Chapter 199 Neutron scattering studies of lanthanide magnetic ordering

“…Zn is found to substitute on ) magnetic Bragg peaks in a pure single crystal of PrBa 2 Cu 3 O 7 (Uma et al 1998a). …”

“…In a fully oxygenated single crystal the Cu spins order at 281 K, while the Pr moments order at 16.8 K as shown in fig. 15 (Uma et al 1998a). The initial ordering is revealed by the intensity of the ( 2 )-type peak as indicated in the bottom of the figure.…”

“…The chain doping can also reduce the Néel temperature for the Pr ordering, and can change the nature of the Pr structure along the c-direction (Longmore et al 1996, Boothroyd et al 1997, Boothroyd 1998 so that the usual c-axis antiferromagnetic coupling is not found in these samples. During the course of these investigations there was also a suggestion from NMR measurements (Nehrke and Pieper 1996) that the Pr was actually non-magnetic in pure Pr 1-2-3, but a reinvestigation with neutrons (Skanthakumar et al 1997b) on pure powders indicated that the Pr was indeed ordering, and this has also been confirmed on pure crystals by neutrons (Uma et al 1998a) and by resonant X-ray scattering (Hill et al 1998). It therefore appears likely that the NMR may have been detecting some Pr on the Ba site in that sample, which may well be in a nonmagnetic singlet crystal-field state, while the line due to the Pr on the R site is too broad to observe.…”

Tunnel magnetoresistance in La0.7Ca0.3MnO3∕PrBa2Cu3O7∕La0.7Ca0.3MnO3

“…3, we display the TMR measured at a bias voltage of V dc = 10 mV as a function of magnetic field for LCMO ͑8 nm͒/PBCO ͑2.4 nm͒/LCMO ͑50 nm͒ junction measured at temperatures ranging from 80 to 110 K. The temperature has been kept in this range to avoid complications due to the antiferromagnetic transition known to occur in the barrier material at lower temperatures. 15 The junction area was 50 ϫ 50 ͑ m͒ 2 . TMR was defined as TMR= ͑R ap − R p ͒ / R p , where R ap and R p are, respectively, the tunnel resistances in the antiparallel and parallel magnetization configurations.…”