Analysis of the magnetocaloric effect in Heusler alloys: study of Ni50CoMn36Sn13 by calorimetric techniques

This is an open access article distributed under the Creative Commons Attribution License.Direct determinations of the isothermal entropy increment, −ΔST, in the Heusler alloy Ni50CoMn36Sn13 on demagnetization gave positive values, corresponding to a normal magnetocaloric effect. These values contradict the results derived from heat-capacity measurements and also previous results obtained from magnetization measurements, which indicated an inverse magnetocaloric effect, but showing different values depending on the technique employed. The puzzle is solved, and the apparent incompatibilities are quantitatively explained considering the hysteresis, the width of the martensitic transition and the detailed protocol followed to obtain each datum. The results show that these factors should be analyzed in detail when dealing with Heusler alloys.Financial support from Projects MAT2011-23791, MAT2013-44063-R and MAT2014-53921-R from the Spanish MEC, DGA Consolidated Groups E100 and E34, RFBR 12-07-00676-a, RF President MD-770.2014.2, RSF 14-12-00570 and from the Ministry of Education and Science of the Russian Federation in the framework of the Increase Competitiveness Program of MISiS are acknowledged.We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).Peer Reviewe

Analysis of the magnetocaloric effect in Heusler alloys: Study of Ni50CoMn36Sn13 by calorimetric techniques

Direct determinations of the isothermal entropy increment, -¿ST , in the Heusler alloy Ni50CoMn36Sn13 on demagnetization gave positive values, corresponding to a normal magnetocaloric effect. These values contradict the results derived from heat-capacity measurements and also previous results obtained from magnetization measurements, which indicated an inverse magnetocaloric effect, but showing different values depending on the technique employed. The puzzle is solved, and the apparent incompatibilities are quantitatively explained considering the hysteresis, the width of the martensitic transition and the detailed protocol followed to obtain each datum. The results show that these factors should be analyzed in detail when dealing with Heusler alloys