17,137 research outputs found
Ferromagnetic ground state of the robust charge-ordered manganite Pr(0.5)Ca(0.5MnO(3)obtained by minimal Al-substitution
We show that minimal disturbance to the robust charge ordered
Pr(0.5)Ca(0.5)MnO(3) by 2.5% Al substitution on Mn-site drives the system
towards ferromagnetic ground state. The history-dependent coexisting phases
observed are explained as an outcome of a hindered first order transition with
glass like arrest of kinetics resulting in irreversibility. Consistent with a
simple phase diagram having ferromagnetic ground state, it is experimentally
shown that these coexisting phases are far from the equilibrium.Comment: This version is Accepted in Physical Review
Coexisting tuneable fractions of glassy and equilibrium long-range-order phases in manganites
Antiferromagnetic-insulating(AF-I) and the ferromagnetic-metallic(FM-M)
phases coexist in various half-doped manganites over a range of temperature and
magnetic field, and this is often believed to be an essential ingredient to
their colossal magnetoresistence. We present magnetization and resistivity
measurements on Pr(0.5)Ca(0.5)Mn(0.975)Al(0.025)O(3) and Pr(0.5)Sr(0.5)MnO(3)
showing that the fraction of the two coexisting phases at low-temperature in
any specified measuring field H, can be continuously controlled by following
designed protocols traversing field-temperature space; for both materials the
FM-M fraction rises under similar cooling paths. Constant-field temperature
variations however show that the former sample undergoes a 1st order transition
from AF-I to FM-M with decreasing T, while the latter undergoes the reverse
transition. We suggest that the observed path-dependent phase-separated states
result from the low-T equilibrium phase coexisting with supercooled glass-like
high temperature phase, where the low-T equilibrium phases are actually
homogeneous FM-M and AF-I phases respectively for the two materials
Relativistic Coupled-Cluster Theory of Atomic Parity Nonconservation: Application to Ba
We report the result of our {\it ab initio} calculation of the parity nonconserving electric dipole transition amplitude in
based on relativistic coupled-cluster theory. Considering
single, double and partial triple excitations, we have achieved an accuracy of
less than one percent. If the accuracy of our calculation can be matched by the
proposed parity nonconservation experiment in Ba for the above
transition,then the combination of the two results would provide an independent
non accelerator test of the Standard Model of particle physics.Comment: 4 pages, 1 figure, Submitted to PR
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