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Magnetic properties and giant magnetocaloric effect (GMCE) of Mn-based Heusler compounds such as Co-Mn-Si, Ni-Mn-Sn, Ni-Mn-Sb have been investigated. The results show that the structure strongly influences on magnetic properties and GMCE of these alloys. The coexistence of ferromagnetic (FM) and antiferromagnetic (AFM) orders is observed. The magnetic phase transitions can be controlled by changing composition and annealing condition of the alloys. GMCEs with large magnitude and wide working temperature range have been obtained on these alloys showing their application potential for magnetic refrigeration technology. | Communications in Physics, Vol. 23, No. 2 (2013), pp. 139-146 MAGNETIC PROPERTIES AND GIANT MAGNETOCALORIC EFFECT IN Mn-BASED HEUSLER COMPOUNDS NGUYEN HUY DAN Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam NGUYEN MANH AN Hong Duc University, 565 Quang Trung, Dong Ve, Thanh Hoa Received 02 April 2013; revised manuscript received 31 May 2013 Accepted for publication 10 June 2013 Abstract. Magnetic properties and giant magnetocaloric effect (GMCE) of Mn-based Heusler compounds such as Co-Mn-Si, Ni-Mn-Sn, Ni-Mn-Sb have been investigated. The results show that the structure strongly influences on magnetic properties and GMCE of these alloys. The coexistence of ferromagnetic (FM) and antiferromagnetic (AFM) orders is observed. The magnetic phase transitions can be controlled by changing composition and annealing condition of the alloys. GMCEs with large magnitude and wide working temperature range have been obtained on these alloys showing their application potential for magnetic refrigeration technology. I. INTRODUCTION Heusler alloys have been attracting a lot of scientists by virtue of their giant magnetocaloric effect (GMCE) and application potential for magnetic refrigeration [1-8]. The magnetic refrigeration bases on the principle of magnetic entropy change of the materials under variation of magnetic field. The application of magnetocaloric materials in the refrigerators has the advantages of avoiding the environmental pollution (unlike the refrigerators using compression gases), improving the cooling efficiency (saving energy), reducing noise and fitting to some special cases. The main problems to be addressed to improve the practical applications of the magnetocaloric materials are: i) creating GMCE in low field, because it is very difficult to create a large magnetic field in the home appliances; ii) taking the magnetic phase transition temperature (working temperature) of materials .
