Heysler Ni_2+x+yMn_1-xGa_1-y ferromagnetic alloys with shape memory effect as on temperature, pressure, so on outer magnetic field are owing a number of phase transitions (PT) depending on stechiometric constitution and alloying with other elements (Fe, Co, Al, etc.): ferromagnetic, premartensitic, martensitic and orientational PTs. With some constitutions of Heysler alloys PTs can be realized at room temperature. For Ni_2.15Mn_0.81Fe_0.04Ga temperatures of martensite-austenite transition and Curie are T_M=325 K and T_K=375 K and for Ni₅₃Mn₂₅Ga₂₂ , Ni_2.18Mn_0.82Ga magnetic and structure PTs are coinciding.

Ferromagnetic films of Heysler alloys are showing PT at lower temperatures and magnetic fields in comparison with volumetric specimen. They also have substantial magnetodeformations (~1%) causing change of form surface and reallocation of a “down spin” electrons and “up” ones. Most strong influence of magnetodeformations on spin-electron transport is supposed to be in nanofilms of Heysler Ni₅₃Mn₂₅Ga₂₂ and Ni_2.18Mn_0.82Ga alloys with combined magnetostructure transition.

A quantum-mechanical calculation of quantum stages and zone structure of spoken above compositions was carried out with taking into account hybridization of s and d(f) electrons FPLMTO method. Computer modeling used molecular dynamics and half-electric quantum-mechanical methods. Shown that ~1% magnetodeformation in Ni53Mn25Ga22 causes spin reorientation in ~10% free electrons.

Author is grateful for BRFFI-RFFI F04R-080 grant for partial financial support

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