13,620 research outputs found
Irreversibility of field-induced magnetostructural transition in NiCoMnSb shape memory alloy revealed by magnetization, transport and heat capacity studies
The effects of magnetic field on the martensitic transition have been studied
in Ni45Co5Mn38Sb12. We find a large field-induced irreversibility in this
system, as revealed by the field dependence of resistivity, magnetization, and
heat capacity data. At the critical temperature, the field-induced conversion
of the martensitic to austenite phase is not reversible under any field
variation. At this temperature any energy fluctuation induces nucleation and
growth of the equilibrium austenite phase at the expense of the metastable
martensitic phase and gets arrested. All these three measurements completely
rule out the coexistence of austenite and martensitic phases in the
irreversibility regime.Comment: 13 pages, 4 figure
Pressure induced magnetic and magnetocaloric properties in NiCoMnSb Heusler alloy
The effect of pressure on the magnetic and the magnetocaloric properties
around the martensitic transformation temperature in NiCoMnSb Heusler alloy has
been studied. The martensitic transition temperature has significantly shifted
to higher temperatures with pressure, whereas the trend is opposite with the
application of applied magnetic field. The maximum magnetic entropy change
around the martensitic transition temperature for Ni45Co5Mn38Sb12 is 41.4 J/kg
K at the ambient pressure, whereas it is 33 J/kg K at 8.5 kbar. We find that by
adjusting the Co concentration and applying suitable pressure, NiCoMnSb system
can be tuned to achieve giant magnetocaloric effect spread over a large
temperature span around the room temperature, thereby making it a potential
magnetic refrigerant material for applications.Comment: 16 pages, 5 figure
Star Clusters in the Magellanic Clouds-1: Parameterisation and Classification of 1072 Clusters in the LMC
We have introduced a semi-automated quantitative method to estimate the age
and reddening of 1072 star clusters in the Large Magellanic Cloud (LMC) using
the Optical Gravitational Lensing Experiment (OGLE) III survey data. This study
brings out 308 newly parameterised clusters. In a first of its kind, the LMC
clusters are classified into groups based on richness/mass as very poor, poor,
moderate and rich clusters, similar to the classification scheme of open
clusters in the Galaxy. A major cluster formation episode is found to happen at
125 +- 25 Myr in the inner LMC. The bar region of the LMC appears prominently
in the age range 60 - 250 Myr and is found to have a relatively higher
concentration of poor and moderate clusters. The eastern and the western ends
of the bar are found to form clusters initially, which later propagates to the
central part. We demonstrate that there is a significant difference in the
distribution of clusters as a function of mass, using a movie based on the
propagation (in space and time) of cluster formation in various groups. The
importance of including the low mass clusters in the cluster formation history
is demonstrated. The catalog with parameters, classification, and cleaned and
isochrone fitted CMDs of 1072 clusters, which are available as online material,
can be further used to understand the hierarchical formation of clusters in
selected regions of the LMC.Comment: 19 pages, 19figures, published in MNRAS on August 16, 2016
Supplementary material is available in the MNRAS websit
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