Investigation of spin gapless semiconducting behaviour in quaternary CoFeMnSi Heusler alloy thin films on Si (1 0 0)

Disordered spin gapless semiconducting CoFeCrGa Heusler alloy thin films on Si (100): experiment and theory

“…CoFeMnSi, Ti 2 MnAl, CFCG, Mn 2 CoAl and CrVTiAl. 10,[16][17][18][19]31,37 It can be seen that the resistivity decreases nearly linearly with temperature which is very different from the case of classical semiconductors, where the resistivity decreases exponentially with temperature. A similar behaviour of resistivity with a negative temperature coefficient has also been observed in transition metal alloys, which is reportedly caused by strong impurity scattering.…”

“…We have also observed that in the given temperature range (5–300 K), the value of σ xx swings from 5705 S cm −1 to 7127 S cm −1 , which is comparable to the room temperature value reported for the CoFeMnSi thin SGS film (5785 S cm −1 ) and slightly higher than that of the bulk SGS Heusler CFCG (4545 S cm −1 ). 31,40…”

“…The decrease in H C with temperature is accompanied by a reduction in the anisotropy field with temperature and also in part due to the weakening of the strength of pinning of the domain walls in the intergranular regions, which is typical in polycrystalline films, like the one in the present study. 31 The value of M S is found to vary from 1.86μ B per f.u. (at 5 K) to 1.81μ B per f.u.…”

“…We have also observed that in the given 44 temperature range (5-300 K), the value of σ xx swings from 5705 S cm −1 to 7127 S cm −1 , which is comparable to the room temperature value reported for the CoFeMnSi thin SGS film (5785 S cm −1 ) and slightly higher than that of the bulk SGS Heusler CFCG (4545 S cm −1 ). 31,40 In order to explain the temperature dependence of resistivity we have considered CFCG here as a disordered-SGS and adopted the two-carrier model used by Kharel et al 40 Kharel et al modelled the conductivity of the majority spin channel for spin narrow-gap semiconductors, spin gapless semiconductors and disordered spin-gapless semiconductors. The model assumes that one spin channel for disordered-SGSs has a band overlap while another channel has a semiconducting band gap, the schematic of which is shown in Fig.…”

“…Several reports confirmed the range of carrier concentration of SGS materials. 16,31,48 The AHE resistivity, i.e., ρ AH majorly arises because of two contributions: (I) intrinsic contribution and (II) extrinsic contribution. The intrinsic contribution particularly relies upon the band structure of the system and is highly independent of impurity induced or SOC-induced scattering, while the reverse is true for the extrinsic contribution.…”