Magnetic shape-memory alloys: phase transitions and functional properties

Buchelnikov, V. D.; Васильев, А. Н.; Koledov, V. V.; Taskaev, S.V.; Ховайло, В. В.; Шавров, В. Г.

doi:10.3367/ufnr.0176.200608j.0900

Cited by 22 publications

(8 citation statements)

References 50 publications

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“…Among ferromagnetic (FM) materials having acceptable magnetocaloric properties, Ni-Mn-Ga Heusler alloys have been widely investigated by experimental and theoretical methods in view of their potential applications as intelligent functional materials [1][2][3][4][5]. The multifunctional properties usually appear across a martensitic transformation due to the strong coupling of crystal structure and magnetic order.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio and Monte Carlo Approaches For the Magnetocaloric Effect in Co- and In-Doped Ni-Mn-Ga Heusler Alloys

Sokolovskiy

Grünebohm

Buchelnikov

et al. 2014

Entropy

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Abstract:The complex magnetic and structural properties of Co-doped Ni-Mn-Ga Heusler alloys have been investigated by using a combination of first-principles calculations and classical Monte Carlo simulations. We have restricted the investigations to systems with 0, 5 and 9 at% Co. Ab initio calculations show the presence of the ferrimagnetic order of austenite and martensite depending on the composition, where the excess Mn atoms on Ga sites show reversed spin configurations. Stable ferrimagnetic martensite is found for systems with 0 (5) at% Co and a c/a ratio of 1.31 (1.28), respectively, leading to a strong competition of ferro-and antiferro-magnetic exchange interactions between nearest neighbor Mn atoms. The Monte Carlo simulations with ab initio exchange coupling constants as input parameters allow one to discuss the behavior at finite temperatures and to determine magnetic transition temperatures. The Curie temperature of austenite is found to increase with Co, while the Curie temperature of martensite decreases with increasing Co content. This behavior can be attributed to the stronger Co-Mn, Mn-Mn and Mn-Ni exchange coupling constants in austenite compared to the corresponding ones in martensite. The crossover from a direct to inverse magnetocaloric effect in Ni-Mn-Ga due to the substitution of Ni by Co leads to the appearance of a "paramagnetic gap" in the martensitic phase. Doping with In increases the magnetic jump at the martensitic transition temperature. The simulated magnetic and magnetocaloric properties of Co-and In-doped Ni-Mn-Ga alloys are in good qualitative agreement with the available experimental data.

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Section: Introductionmentioning

confidence: 99%

Ab Initio and Monte Carlo Approaches For the Magnetocaloric Effect in Co- and In-Doped Ni-Mn-Ga Heusler Alloys

Sokolovskiy

Grünebohm

Buchelnikov

et al. 2014

Entropy

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“…Previous studies have shown that it is possible to tune the temperature at which this transition occurs by, for example, varying the composition of iron or rhodium [8], doping with other elements [2,8,9], such as Pd, Pt, or Ir, or straining the sample [10]. Excitation of the phase transition occurs when energy is added to the system allowing one to use a wide range of stimuli to induce the metamagnetic phase transition, such as, electric field [11], temperature [1], applied magnetic fields [12,13], pressure [14], and spin-polarized currents [15] making it a tempting candidate for future magnetic-based technological devices.…”

Section: Introductionmentioning

confidence: 99%

Modeling the thickness dependence of the magnetic phase transition temperature in thin FeRh films

et al. 2017

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FeRh and its first-order phase transition can open new routes for magnetic hybrid materials and devices under the assumption that it can be exploited in ultra-thin-film structures. Motivated by experimental measurements showing an unexpected increase in the phase transition temperature with decreasing thickness of FeRh on top of MgO, we develop a computational model to investigate strain effects of FeRh in such magnetic structures. Our theoretical results show that the presence of the MgO interface results in a strain that changes the magnetic configuration which drives the anomalous behavior.

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“…In recent decades the ferromagnetic nickel Heusler alloys with shape memory effect (SME) and, particularly, NiFeGaCo are studied intensively by many researchers [1][2][3][4][5]. These crystals are interesting due to possibility of obtaining the large reversible magnetically-induced deformations, superelasticity (SE), and effect of high-speed recovery of shape memory deformation (HSROSMD).…”

Section: Introductionmentioning

confidence: 99%

Formation of a dendrite structure in crystals NiFeGaCo alloy in the process of growing by the Stepanov method

Krymov

M.G.

et al. 2022

Physics of the Solid State

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The process of growing crystals of the NiFeGaCo alloy by the Stepanov method has been developed. It was found that the structural perfection is disturbed by the formation of dendrites, which are distributed inhomogeneously both along the length and in the cross sections of the crystals. The blocking effect of the dendrites on growth crystals of the martensite phase, which appears when the samples are cooled to the temperature of the transition of the crystal to the martensite state, is found. The elemental composition of dendritic formations was studied and it was shown that the iron content in the dendrite is approximately 30% higher, and the gallium content is 40% lower than in the matrix. Based on the modeling of heat transfer processes in the real growth zone, taking into account the experiments performed, recommendations were obtained for suppressing the formation of dendrites Keywords: Dendritic structure, shape memory alloys, Stepanov's method.

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Magnetic shape-memory alloys: phase transitions and functional properties

Cited by 22 publications

References 50 publications

Ab Initio and Monte Carlo Approaches For the Magnetocaloric Effect in Co- and In-Doped Ni-Mn-Ga Heusler Alloys

Ab Initio and Monte Carlo Approaches For the Magnetocaloric Effect in Co- and In-Doped Ni-Mn-Ga Heusler Alloys

Modeling the thickness dependence of the magnetic phase transition temperature in thin FeRh films

Formation of a dendrite structure in crystals NiFeGaCo alloy in the process of growing by the Stepanov method

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