Effect of deposition temperature on the structure, magnetic and transport properties in Co2MnSi Heusler films

Abstract

The various Co 2 MnSi films, from chemical ordered L2 1 state to completely disordered amorphous state, were prepared on glass substrates with different deposition/annealing temperatures. The influence of deposition/annealing temperature on the crystallographic defects and atomic disorders, and further on the magnetic and transport properties of the Co 2 MnSi films were investigated in detail. The decrease in crystallinity leads to the structure disorder, spin disorder and further the reduction of magnetization as well as the increase of residual resistivity. The dominant source in anomalous Hall effect for the polycrystalline samples is the skew scattering, while the skew scattering coefficient a becomes larger with the increasing deposition temperature, due to the increase of skew scattering center introduced by the increasing structure disorder.

Alternating current susceptibility and magnetisation of nanocrystalline Co2MnSi Heusler alloy films

“…The CMS/(Si, MgO) films exhibiting the nanocrystalline grains with an A2 type disorder (when grown or annealed at T ≤ 300°C) demonstrated relatively high resistivity values (ρ ~ 0.3 ÷ 0.4 mΩ cm at 295 K) which are typical of highly disordered metallic alloys. The negative temperature coefficient of resistance (TCR) with the ratio ρ(300)/ρ(78) ranging from 0.9 to 0.97 has been indicated for these films in a good accordance with earlier observations [7,8]. The reduced resistivity and positive TCR values, ρ(300)/ρ(78) ≅ 1.0 ÷ 1.2, have been indicated for the films either annealed or deposited in situ at T ≥ 400°C.…”

“…The CMS compound crystallizes in a cubic structure. Three different types of structural configurations, namely L2 1 , B2 and A2, depending on the chemical ordering degree of the constituent elements, have been reported [5][6][7][8]. The L2 1 structure demonstrating the highest chemical order (space group Fm -3m) is composed of four interpenetrating f.c.c.…”

“…The effects of deposition/annealing temperature on the crystalline structure, magnetic and transport properties of CMS films were studied by a number of authors [7,11]. However, up to date, the evolution of magnetic and magnetotransport properties in the films has not yet been fully understood.…”

“…The major magnetic properties, namely the coercive field Magnetic and electrical properties of the CMS compound are known to depend on a crystalline structure and chemical ordering of the constituent elements. Ordering of atoms in CMS films was found to depend on a number of factors such as crystalline quality, atomic composition, deposition conditions and post-annealing [2,[5][6][7][8][9][10].…”

“…Various deposition techniques such as magnetron sputtering [9][10][11], molecular beam epitaxy [12], laser ablation [8] and plasma-assisted sputtering [13] have been employed for the growth of the CMS films using various substrates such as crystalline Si [5,9,11], Al 2 O 3 [6,14], MgO [6,8], GaAs [15], Ge [12] and amorphous glass [7].…”