Reversible magnetocaloric effect in materials with first order phase transitions in cyclic magnetic fields: Fe48Rh52 and Sm0.6Sr0.4MnO3

Themagnetocaloric effect (MCE) in an Fe48Rh52 alloy and Sm0.6Sr0.4MnO3 manganite was studied in cyclicmagnetic fields. The adiabatictemperature change in the Fe48Rh52 alloy for amagnetic field change ( ΔB) of 8  T and a frequency (f) of 0.13  Hz reaches the highest value of (ΔTad) of −20.2 K at 298 K. The magnitude of the MCE in Sm0.6Sr0.4MnO3 reaches ΔTad = 6.1 K at the samemagnetic field change at 143  K. Thetemperature regions, where a strong MCE is exhibited in an alternatingmagnetic field, are bounded in both compounds. In the case of the Fe48Rh52 alloy, thetemperature range for this phenomenon is bounded above by theferromagnetic to antiferromagnetictransitiontemperature in the zero field condition during cooling. In the case of the Sm0.6Sr0.4MnO3 manganite, thetemperature range for the MCE is bounded below by theferromagnetic-paramagnetictransitiontemperature in zero field during heating. The presence of these phase boundaries is a consequence of the existence of areas of irreversible magnetic-field-inducedphase transitions. It is found that the effect of long-term action of thousands of cycles ofmagnetization/demagnetization degrades themagnetocaloricproperties of the Fe48Rh52 alloy. This can be explained by the gradual decrease in the size of theferromagnetic domains and increasing role of the domain walls due to giant magnetostriction at theferromagnetic to antiferromagnetictransitiontemperature. The initialmagnetocaloricproperties can be restor...

Source: Applied Physics Letters - November 17, 2016 Category: Physics Authors: A. M. Aliev, A. B. Batdalov, L. N. Khanov, A. P. Kamantsev, V. V. Koledov, A. V. Mashirov, V. G. Shavrov, R. M. Grechishkin, A. R. Kaul' and V. Sampath Source Type: research