2,194 research outputs found
Antiferromagnetism at the YBa2Cu3O7 / La2/3Ca1/3MnO3 interface
The magnetic properties of a series of YBa2Cu3O7-x/La2/3Ca1/3MnO3
(YBCO/LC1/3MO) superlattices grown by dc sputtering at high oxygen pressures
(3.5 mbar) show the expected ferromagnetic behaviour. However, field cooled
hysteresis loops at low temperature show the unexpected existence of exchange
bias, effect associated with the existence of ferromagnetic/antiferromagnetic
(F/AF) interfaces. The blocking temperature (TB) is found thickness dependent
and the exchange bias field (HEB) is found inversely proportional to the FM
layer thickness, as expected. The presence of an AF material is probably
associated to interface disorder and Mn valence shift towards Mn4+.Comment: 12 pages, 2 figures, 1 table, submitted to Applied Physics Letter
Magnons in Ferromagnetic Metallic Manganites
Ferromagnetic (FM) manganites, a group of likely half-metallic oxides, are of
special interest not only because they are a testing ground of the classical
doubleexchange interaction mechanism for the colossal magnetoresistance, but
also because they exhibit an extraordinary arena of emergent phenomena. These
emergent phenomena are related to the complexity associated with strong
interplay between charge, spin, orbital, and lattice. In this review, we focus
on the use of inelastic neutron scattering to study the spin dynamics, mainly
the magnon excitations in this class of FM metallic materials. In particular,
we discussed the unusual magnon softening and damping near the Brillouin zone
boundary in relatively narrow band compounds with strong Jahn-Teller lattice
distortion and charge/orbital correlations. The anomalous behaviors of magnons
in these compounds indicate the likelihood of cooperative excitations involving
spin, lattice, as well as orbital degrees of freedom.Comment: published in J. Phys.: Cond. Matt. 20 figure
Signature of Magnetic Phase Separation in the Ground State of Pr1-xCaxMnO3
Neutron scattering has been used to investigate the evolution of the long-
and short-range charge-ordered (CO), ferromagnetic (FM), and antiferromagnetic
(AF) correlations in single crystals of Pr1-xCaxMnO3. The existence and
population of spin clusters as refected by short-range correlations are found
to drastically depend on the doping (x) and temperature (T). Concentrated spin
clusters coexist with long-range canted AF order in a wide temperature range in
x = 0.3 while clusters do not appear in x = 0.4 crystal. In contrast, both CO
and AF order parameters in the x = 0.35 crystal show a precipitous decrease
below ~ 35 K where spin clusters form. These results provide direct evidence of
magnetic phase separation and indicate that there is a critical doping x_c
(close to x = 0.35) that divides the phase-separated site-centered from the
homogeneous bond-centered or charge-disproportionated CO ground state.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Letter
-Nucleus Scattering at Low and Intermediate Energies
We calculate -nucleus elastic differential, reaction and total cross
sections for different nuclei (C,Ca and Pb) at several
laboratory antikaon momenta, ranging from 127 MeV to 800 MeV. We use different
antikaon-nucleus optical potentials, some of them fitted to kaonic atom data,
and study the sensitivity of the cross sections to the considered
antikaon-nucleus dynamics.Comment: Only 4 pages, Latex, 3 Figures. This version is much shorter than the
previous one. Some details and references have been omitte
Spin Wave Response in the Dilute Quasi-one Dimensional Ising-like Antiferromagnet CsCo_{0.83}Mg_{0.17}Br_3
Inelastic neutron scattering profiles of spin waves in the dilute
quasi-one-dimensional Ising-like antiferromagnet CsCo_{0.83}Mg_{0.17}Br_3 have
been investigated. Calculations of S^{xx}(Q,omega), based on an effective spin
Hamiltonian, accurately describe the experimental spin wave spectrum of the 2J
mode. The Q dependence of the energy of this spin wave mode follows the
analytical prediction
omega_{xx}(Q)=(2J)(1-5epsilon^{2}cos^{2}Qa+2epsilon^{2})^{1/2}, calculated by
Ishimura and Shiba using perturbation theory.Comment: 13 pages, 4 figure
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