Strain-relaxation induced transverse resistivity anomaly in epitaxial films through lithography engineering

The exotic transverse resistivity in magnetic materials has received intense research because of possible new emergent physics. Here, we report the strain-relaxation induced transverse resistivity anomaly in Mn CoAl epitaxial films through lithography engineering. The anomalous Hall resistivityρxyAHdecreases from 0.48 to 0.17 Ω cm at 10 K when the widths of the Hall bar decreases from 40 to 1 m, and the temperature dependence ofρxyAHreverses for the 1.4 m deep-etched samples. Importantly, Hall resistivity anomalies appear in the 1 m-wide and 1.4 m-wide deep-etched Hall bar samples, which can be well explained by the two-channel transport mechanism. We believe that these observations can be attributed to the strain relaxation effect when the Hall bar width is narrowed to around 1 m. Our work shows that the induced strain relaxation can possibly lead to the alternation of the materials' electronic structure, and the size effect should be considered when the sample size is reduced to about 1 m.