80,825 research outputs found
Conversion of glassy antiferromagnetic-insulating phase to equilibrium ferromagnetic-metallic phase by devitrification and recrystallization in Al substituted PrCaMnO
We show that PrCaMnO with 2.5% Al substitution and
LaCaMnO (LCMO) exhibit qualitatively similar and
visibly anomalous M-H curves at low temperature. Magnetic field causes a broad
first-order but irreversible antiferromagnetic (AF)-insulating (I) to
ferromagnetic (FM)-metallic (M) transition in both and gives rise to soft FM
state. However, the low temperature equilibrium state of
PrCaMnAlO (PCMAO) is FM-M whereas that
of LCMO is AF-I. In both the systems the respective equilibrium phase coexists
with the other phase with contrasting order, which is not in equilibrium, and
the cooling field can tune the fractions of the coexisting phases. It is shown
earlier that the coexisting FM-M phase behaves like `magnetic glass' in LCMO.
Here we show from specially designed measurement protocols that the AF-I phase
of PCMAO has all the characteristics of magnetic glassy states. It devitrifies
on heating and also recrystallizes to equilibrium FM-M phase after annealing.
This glass-like AF-I phase also shows similar intriguing feature observed in
FM-M magnetic glassy state of LCMO that when the starting coexisting fraction
of glass is larger, successive annealing results in larger fraction of
equilibrium phase. This similarity between two manganite systems with
contrasting magnetic orders of respective glassy and equilibrium phases points
toward a possible universality.Comment: Highlights potential of CHUF (Cooling and Heating in Unequal Fields),
a new measurement protoco
Erasing Distinguishability Using Quantum Frequency Up-Conversion
The frequency distinguishability of two single photons was successfully
erased using single photon frequency up-conversion. A frequency non-degenerate
photon pair generated via spontaneous four-wave mixing in a dispersion shifted
fiber was used to emulate two telecom-band single photons that were in the same
temporal mode but in different frequency modes. The frequencies of these
photons were converted to the same frequency by using the sum frequency
generation process in periodically poled lithium niobate waveguides, while
maintaining their temporal indistinguishability. As a result, the two converted
photons exhibited a non-classical dip in a Hong-Ou-Mandel quantum interference
experiment. The present scheme will add flexibility to networking quantum
information systems that use photons with various wavelengths.Comment: 4 pages, 5 figure
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