Interstitial-nitrogen effect on phase transition and magnetocaloric effect in Mn(As,Si) (invited)

Abstract

The effect of interstitial nitrogen on the phase transition and magnetocaloric behavior of [formula omitted] ([formula omitted], 0.06, and 0.09) is investigated. The interstitial nitrogen atoms cause the step-scanned x-ray diffraction peaks to shift toward lower angles and lower the Curie temperature, whereas silicon addition increases the Curie temperature to near room temperature. The thermal hysteresis is reduced to nearly 0 in [formula omitted], which is beneficial to practical applications. For a field change of 5 T, the largest magnetic entropy change and refrigerant capacity are [formula omitted] at 247 K and [formula omitted], which is slightly higher than the entropy change in the parent alloy. Finally, we briefly discuss the occurrence and origin of the “virgin effect” in MnAs. © 2010, American Institute of Physics. All rights reserved.