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