Analysis of Strain Response of Resistance in Cr-(N,Al) using First-Principles Calculations

We studied the strain response of resistivity in Cr-N and Cr-Al, where a small amount of N or Al (<10 at.%) was doped into antiferromagnetic Cr, using first-principles electronic structure calculations. Interstitial-type model (Cr16N1) and substitutional-type model (Cr15N1, Cr15Al1) were considered to analyze the strain dependence of magnetic and conduction properties. The calculation results reveal that an antiferromagnetic order is maintained in Cr16N1, Cr15N1, and Cr15Al1 despite the doping of nonmagnetic elements such as N or Al, and that the magnetic moment of Cr atom and the electrical resistivity in these materials shows high strain sensitivity. In particular, the gauge factor estimated from the strain dependence of the density of states at the Fermi level is approximately 5 ∼ 10, in good agreement with experimental observations. The sensitive response in Cr16N1, Cr15N1, and Cr15Al1 is attributed to a characteristic property of antiferromagnetic Cr, in that volume variation accompanying uniaxial strain influences its electronic structure and magnetism through the magnetovolume effect.