Reducing extrinsic hysteresis in first-order La(Fe,Co,Si)13 magnetocaloric systems

Abstract

Simultaneous magnetization and sample temperature measurements were performed as a function of magnetic field and magnetic field sweep-rates to study the influence of these conditions on the hysteresis of the magnetocaloric transition in La(Fe1−x−yCoxSiy)13 samples. The large magnetocaloric effect in the compounds that show a first-order transition cause a significant departure from isothermal conditions leading to dynamic sweep-rate dependent magnetic hysteresis. Here we show how this deleterious effect can be greatly reduced by changing the sample geometry or by use of materials which show a second-order transition only. The key signatures of nonisothermal conditions in the magnetization data are highlighted.