Abstract. The magnetic and magnetocaloric properties of La_0.8Sm_0.2Mn₂Si₂ and La_0.775Gd_0.225Mn₂Si₂ compounds have been studied by temperature- and magnetic field-dependent magnetic measurements. Both compounds crystallize in the ThCr₂Si₂-type structure with the space group I4/mmm. Both compounds exhibit reentrant magnetic phase transitions and field-induced transitions from antiferromagnetic to ferromagnetic or ferrimagnetic state. The isothermal magnetic entropy change is estimated by using the Maxwell relation and Landau theory. Both compounds show inverse and conventional magnetocaloric effects around transition temperatures. Application of Landau theory on magnetic transitions shows good agreement with the result obtained by Maxwell theory.

PACS numbers: 75.50.−y, 75.60.Ej, 75.20.En, 75.30.Sg

Print publication: Issue 5 (November 2009)
Received 14 April 2009, accepted for publication 16 September 2009
Published 27 October 2009