We have studied the multicaloric properties of a Ni-Mn-Ga-Cu alloy. In this alloy, application magnetic field and uniaxial stress shift its martensitic transition towards higher temperatures which results in synergic magnetocaloric elastocaloric effects. By proper numerical treatment calorimetric curves obtained under applied we entropy $S(T,{\ensuremath{\mu}}_{0}H,\ensuremath{\sigma})$ as func...

OF DOCTORAL DISSERTATION HELSINKI UNIVERSITY OF TECHNOLOGY P. O. BOX 1000, FI-02015 TKK http://www.tkk.fi Author Ladislav Straka Name of the dissertation Manuscript submitted 6.2.2007 Manuscript revised 22.5.2007 Date of the defence 15.6.2007 Article dissertation (summary + original articles) Monograph Department Laboratory Field of research Opponent(s) Supervisor Instructor Abstract

Field-induced strains of 6% are reported in ferromagnetic Ni–Mn–Ga martensites at room temperature. The strains are the result of twin boundary motion driven largely by the Zeeman energy difference across the twin boundary. The strain measured parallel to the applied magnetic field is negative in the sample/field geometry used here. The strain saturates in fields of order 400 kA/m and is blocke...