Researchers have found a new alloy that can act as an effective magnetic refrigerant for minimising greenhouse gas emissions meet the global demand for higher energy efficiency to tackle global warming.

Magnetic refrigeration offers an energy-efficient and environment-friendly cooling technology as an alternative to the vapour-cycle refrigeration technology in use today. Hence efforts are on to fabricate magnetic refrigerators for household, industrial and technological applications.

Magnetic cooling effect (MCE) is the reversible temperature change of a magnetic material when it is subjected to an external applied magnetic field. Magnetisation and de-magnetisation leads to the magnet either giving out or absorbing heat.

Current research is focused on developing new magnetic materials for use as refrigerants. The material must be capable of operating for millions of cycles without any fatigue and failure, must have high thermal conductivity and should respond to an external magnetic field of about 2T (Tesla). Since most of the materials developed so far show giant magneto caloric effect (GMCE) with fields reaching as high as 5T, there is an urgent need to look for materials in which GMCE is achieved in lower fields.

Researchers from the SN Bose National Centre for Basic Sciences, Kolkata, experimented with an alloy called all-transition metal-based Heusler alloys (which are magnetic inter-metallics with face-centred cubic crystal structure) in their search for material exhibiting giant reversible MCE. “The search for the right kind of magnetic material has yielded positive results at the SN Bose Centre Lab. The synergistic combinations of giant MCE and MR by proper tailoring of Cu-doped Heusler alloys may lead to a diverse range of solid state-based technological applications,” says a press release from the Department of Science and Technology, Government of India.

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