1,690 research outputs found
Induced antiferromagnetism and large magnetoresistances in RuSr2(Nd,Y,Ce)2Cu2O10-d ruthenocuprates
RuSr2(Nd,Y,Ce)2Cu2O10-d ruthenocuprates have been studied by neutron
diffraction, magnetotransport and magnetisation measurements and the electronic
phase diagram is reported. Separate Ru and Cu spin ordering transitions are
observed, with spontaneous Cu antiferromagnetic order for low hole doping
levels p, and a distinct, induced-antiferromagnetic Cu spin phase in the 0.02 <
p < 0.06 pseudogap region. This ordering gives rise to large negative
magnetoresistances which vary systematically with p in the
RuSr2Nd1.8-xY0.2CexCu2O10-d series. A collapse of the magnetoresistance (MR)
and magnetisation in the pre-superconducting region may signify the onset of
superconducting fluctuations.Comment: 22 pages, 11 figure
Charge and orbital order in frustrated Pb3Mn7O15
The candidate magnetoelectric Pb3Mn7O15 has a structure consisting of 1/3
filled Kagome layers linked by ribbons of edge-sharing octahedra in the
stacking direction. Previous reports have indicated a complex
hexagonal-orthorhombic structural transition upon cooling to room temperature,
although its origins are uncertain. Here both structures are revisited using a
combination of neutron and synchrotron X-ray diffraction data. Large shifts of
oxygen positions are detected which show that the interlayer sites and those
which occupy voids in the kagome lattice are trivially charge ordered in both
phases. The symmetry breaking is found to occur due to Mn3+ orbital ordering on
the ribbon sites and charge ordering of the sub-set of layer sites which make
up a Kagome network.Comment: Minor changes, to appear in J. Phys. Cond. Mat
- …