Interdependence between the magnetic properties and lattice parameters of Ni–Mn–Ga martensite

Abstract

The temperature dependences of both the saturation magnetic field values and the powder diffraction patterns of two Ni-Mn-Ga tetragonal martensites were studied experimentally. A reasonable agreement between the temperature dependences of the lattice parameters determined from the x-ray diffraction data and obtained from the magnetization curves is observed. This experimental finding demonstrates the linear dependence of the magnetic anisotropy constant on the tetragonal distortion of the cubic crystal lattice arising in the course of the martensitic transformation, and hence supports the macroscopic and microscopic theories by L'vov et al (1998 J. Phys.: Condens. Matter 10 4587) and Enkovaara et al (2002 Phys. Rev. B 65 134422), respectively, which predict this dependence.

Magneto-Structural Properties of Ni2MnGa Ferromagnetic Shape Memory Alloy in Magnetic Fields

“…Zhu et al [11] investigated the lattice constant change Δc/c of −4.8% of Ni 51.9 Mn 23.2 Ga 24.9 by means of X-ray diffraction study around martensite transformation temperature. Chernenko et al [12] also studied about magnetization and X-ray powder diffractions, and clear changes were found at T M for both measurements. Murray et al [18] studied the polycrystal Ni-Mn-Ga alloys.…”

“…Several studies on Ni-Mn-Ga alloys have addressed martensite transformation and correlation between magnetism and crystallographic structures [6][7][8][9][10][11][12][13][14][15][16][17][18]. Ma et al [7] studied the crystallography of Ni 50+x Mn 25 Ga 25-x alloys (x = 2-11) by powder X-ray diffraction and optical microspectroscopy.…”

“…The magnetization results indicate that the martensite Ni-Mn-Ga alloys have higher magnetocrystalline anisotropy compared to Mn ferrites. Furthermore, magnetization results indicate that the coercivity and saturation field at the martensite phase are higher than those of the cubic austenite phase [11][12][13][14][15]. Zhu et al [11] investigated the lattice constant change Δc/c of −4.8% of Ni 51.9 Mn 23.2 Ga 24.9 by means of X-ray diffraction study around martensite transformation temperature.…”

Thermal Strain and Magnetization Studies of the Ferromagnetic Heusler Shape Memory Alloys Ni2MnGa and the Effect of Selective Substitution in 3d Elements on the Structural and Magnetic Phase

“…Several studies on Ni-Mn-Ga alloys address the martensite transition and correlation between magnetism and crystallographic structures [6][7][8][9][10][11][12][13][14][15][16][17][18]. Ma et al studied the crystallography of Ni50+xMn25Ga25-x alloys (x = 2-11) by powder X-ray diffraction and optical microspectroscopy [7].…”

“…This is because lower initial permeability or lower magnetization at low fields than the cubic austenite phase. Furthermore, the magnetization results indicate that the coercivity and saturation field at martensite phase are higher than those of the cubic austenite phase [11][12][13][14][15]. Zhu et al investigated the lattice constant change c/c of -4.8 % by means of X-ray diffraction study around martensite transition temperature [11].…”