Eur. Phys. J. B (2012) 85: 19
https://doi.org/10.1140/epjb/e2011-20381-9

Regular Article

Transport properties of Co₂CrAl Heusler alloy films

¹ Institute of Metal Physics, National Academy of Sciences of Ukraine, 252680, 142, Kiev, Ukraine
² q-Psi and Department of Physics, Hanyang University, 133-791 Seoul, Korea
³ Institute of Molecular Physics, Polish Academy of Sciences, 60-179 Poznań, Poland
⁴ Sunmoon University, 336-708 Asan, Korea
⁵ Kwangwoon University, 139-701 Seoul, Korea
⁶ Helmholtz Centre Berlin for Materials and Energy Gmbh, Glienicker Str. 100, 14109 Berlin, Germany

^a e-mail: yplee@hanyang.ac.kr

Received: 18 May 2011
Received in final form: 19 September 2011
Published online: 18 January 2012

Abstract

The effect of atomic disorder on the electron transport and the magnetoresistance (MR) of Co₂CrAl Heusler alloy (HA) films has been investigated. We show that Co₂CrAl films with L2₁ order exhibit a negative value for the temperature coefficient of resistivity (TCR) in a temperature range of 10 < T <  290 K, and the temperature dependence of electric conductivity varies as T^3/2 similarly to that of the zero-gap semiconductors. The atomic or the site disorder on the way of L2₁ →  B2  →  A2  →  amorphous state in Co₂CrAl HA films causes the deviation from this dependence: reduction in the absolute value of TCR as well as decrease in the resistivity down to ϱ(T = 293 K)  ~  200 μΩ cm in comparison to ϱ(T = 293 K)  ~  230 μΩ cm typical for the Co₂CrAl films with L2₁ order. The magnetic-field dependence of MR of the Co₂CrAl films with L2₁ order is determined by two competing contributions: a positive Lorentz scattering and a negative s-d scattering. The atomic disorder in Co₂CrAl films drastically changes MR behavior due to its strong influence on the magnetic properties.