1,626 research outputs found
Room temperature soft ferromagnetism in the nanocrystalline form of YCo2 - a well-known bulk Pauli paramagnet
The Laves phase compound, YCo2, is a well-known exchange-enahnced Pauli
paramagnet. We report here that, in the nanocrystalline form, this compound
interestingly is an itinerant ferromagnet at room temperature with a low
coercive-field. The magnitude of the saturation moment (about 1 Bohr-magneton
per formula unit) is large enough to infer that the ferromagnetism is not a
surface phenomenon in these nanocrystallites. Since these ferromagnetic
nanocrystallines are easy to synthesize with a stable form in air, one can
explore applications, particularly where hysteresis is a disadvantage
Resistive switching in ultra-thin La0.7Sr0.3MnO3 / SrRuO3 superlattices
Superlattices may play an important role in next generation electronic and
spintronic devices if the key-challenge of the reading and writing data can be
solved. This challenge emerges from the coupling of low dimensional individual
layers with macroscopic world. Here we report the study of the resistive
switching characteristics of a of hybrid structure made out of a superlattice
with ultrathin layers of two ferromagnetic metallic oxides, La0.7Sr0.3MnO3
(LSMO) and SrRuO3 (SRO). Bipolar resistive switching memory effects are
measured on these LSMO/SRO superlattices, and the observed switching is
explainable by ohmic and space charge-limited conduction laws. It is evident
from the endurance characteristics that the on/off memory window of the cell is
greater than 14, which indicates that this cell can reliably distinguish the
stored information between high and low resistance states. The findings may
pave a way to the construction of devices based on nonvolatile resistive memory
effects
Exchange bias and training effects in antiferromagnetically coupled La0.7Sr0.3MnO3 / SrRuO3 superlattices
Exchange bias (EB) and the training effects (TE) in an antiferromagnetically
coupled La0.7Sr0.3MnO3 / SrRuO3 superlattices were studied in the temperature
range 1.8 - 150 K. Strong antiferromagnetic (AFM) interlayer coupling is
evidenced from AC - susceptibility measurements. Below 100 K, vertical
magnetization shifts are present due to the two remanent states corresponding
to the two ferromagnetic (FM) layers at FM and AFM coupling condition. After
field cooling (FC), significant decrease in the exchange bias field (HEB) is
observed when cycling the system through several consecutive hysteresis loops.
Quantitative analysis for the variation of HEB vs. number of field cycles (n)
indicates an excellent agreement between the theory, based on triggered
relaxation phenomena, and our experimental observations. Nevertheless, the
crucial fitting parameter K indicates smooth training effect upon repeated
field cycling, in accordance with our observation.Comment: Accepted Europhysics Letter
Magnetocaloric effect and nature of magnetic transition in nanoscale Pr0.5Ca0.5MnO3
Systematic measurements pertinent to the magnetocaloric effect and nature of
magnetic transition around the transition temperature are performed in the 10
nm Pr0.5Ca0.5MnO3 nanoparticles (PCMO10) . Maxwell relation is employed to
estimate the change in magnetic entropy. At Curie temperature TC, 83.5 K, the
change in magnetic entropy discloses a typical variation with a value 0.57 J/kg
K, and is found to be magnetic field dependent. From the area under the curve
Delta S vs T, the refrigeration capacity is calculated at TC, 83.5 K and it is
found to be 7.01 J/kg. Arrott plots infer that due to the competition between
the ferromagnetic and anti ferromagnetic interactions, the magnetic phase
transition in PCMO10 is broadly spread over both in temperature as well as in
magnetic field coordinates. Upon tuning the particle size, size distribution,
morphology, and relative fraction of magnetic phases, it may be possible to
enhance the magnetocalorific effect further in PCMO10.Comment: Accepted (Journal of Applied Physics) (In press
The Indian Mackerel; VI Exploitation
The types of fishing craft and gear commonly used in the fishery have been evolved to suit the local
requirement depending upon the physical characteristics of the coastline, surf conditions as well as habits
of fish. Descriptive accounts of the types of these craft and gear, used both on the west and east coasts of
India, are given by Hornell (1910a and 1938), Chopra (1951), Anon. (1941 and 1943), and Zeiner and
Rasmussen (1958). Later Jones and Rosa (1965 and 1967) have listed the important types of fishing craft
and gear commonly employed in the mackerel fishery. Similarly Rao (1969) has shown, among other
things, the most common types of fishing boats and nets used in the Indian waters for this fishery
Food of the Indian mackerel, Rastrelliger kanagurta (Cuvier) taken by drift-nets in the Arabian sea off Vizhingam, South Kerala
Being one of the most important neritic pelagic specie:., the Indian mackerel,
RastrelUger kanagurta (Cuvier), has been, the object of investigations by many
fishery biologists. On the West Coast of India, while this species supports
a rich commercial fishery, its distribution on the East Coast is only of biological
interest. Most of the earlier works (Devanesan and John, 1940;
Devanesan, 1942; John and Menon, 1942 and Chidambaram, 1944) are
of brief notes dealing with the nature of food of the mackerel on the West
Coast of India. In recent years, Chidambaram et al. (1952) have studied in
detail the fat variations, sizo composition, maturity and food habits of the
mackerel. Bhimachar and George (1952) have given a detailed account of
the seasonal fluctuations in the food of this species from Calicut. Mention
should be made of the comprehensive works of Pradhan (1956) and Sekharan
(1958) on the fishery and certain biological aspscts of the mackerel from the
Konkan Coast. Our knowledge on the biology of this species from the East
Coast of India is confined to the recent works of Kuthalingam (1956) from
Madras, Rao and Rao (1957) and Rao (1962) from Waltair
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