Magnetic anisotropy in epitaxial Mn5Ge3films

Magnetic anisotropy and magnetic domain structure in C-doped Mn5Ge3

“…Considering a critical thickness of about 30 nm and the anisotropy constant previously determined, the exchange stiffness in the carbon-doped compound may be estimated to 1.4 pJ/m. This value is greater than the one found in Mn 5 Ge 3 (1 pJ/m), 18 which is consistent with the Curie temperature enhancement.…”

“…4a. The linear behavior of this figure is well described by M 18 a FDL has been formed at the interface between the Ge(111) substrate and the Mn 5 Ge 3 C 0.7 film and its thickness t F DL has been estimated to be (2.0 ± 0.5) nm at 300K and (1.3 ± 0.5) nm at 15 K. This is equal to the value found in Mn 5 Ge 3 within experimental errors.…”

“…This value corresponds to the field necessary to align the magnetization within the DWs in the applied field direction. 18 Little variation in this quantity is noticeable for film thicknesses up to 30nm, whereas, above this value, H Closure starts to increase with thickness, along with the onset of canting of the loops. This suggests a modification of the domain structure around 30 nm.…”

“…A gradual change is observed in the shape of the in-plane hysteresis loops. 18,20 The saturation field increases with thickness giving rise to a more canted curve. This effect, particularly visible in the Mn 5 Ge 3 epilayer, is assigned to a reorientation of the magnetization in thin films with perpendicular anisotropy.…”

“…21 However, the critical thickness is different for the two materials. Whereas a stripe domain structure has just been formed in a 20 nm-Mn 5 Ge 3 film, 18 the square inplane M-H curve measured in a Mn 5 Ge 3 C 0.7 layer with an equivalent thickness is characteristic of completely inplane magnetization. As magnetization remains uniform below the critical thickness, the uniaxial anisotropy K u can be determined from the analysis of M-H curves and has been estimated to be (50 ± 10) kJ/m 3 at 300 K and (60 ± 10) kJ/m 3 at 15 K. The values deduced for 30nm-thick films are very similar.…”