Characteristic electronic transport properties induced by interfacial scattering in Co nanocluster-assembled films

Co nanocluster-assembled films with a thickness between 1200 and 2000 nm were fabricated by plasma-gas condensation technology. These films are composed of stacked Co nanoclusters, each with an average diameter of approximately 8.5 nm, which collectively form a dense three-dimensional (3D) granular network. The results indicate that: (1) The anomalous Hall coefficient ( R s ) for films with thicknesses between 1600 and 2000 nm reached values from 1.24 to 1.24–2.36 × 10 −9 ΩcmG −1 , which is nearly three orders of magnitude greater than that of bulk Co, likely due to their unique microstructure. (2) Electrical transport measurements revealed that the thicker samples (1600–2000 nm) exhibited metallic behavior, while the thinner samples (1200 nm and 1400 nm) demonstrated a minimum in longitudinal resistivity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mrow> <mml:msub> <mml:mi>ρ</mml:mi> <mml:mrow> <mml:mi>x</mml:mi> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:mrow> </mml:math> ) at specific temperatures, following a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>−</mml:mo> <mml:mrow> <mml:mtext>log</mml:mtext> </mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> </mml:math> relationship. (3) In the high-temperature range, the scaling exponent ( γ ) derived from fitting the saturated anomalous Hall resistivity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>ρ</mml:mi> <mml:mrow> <mml:mi>x</mml:mi> <mml:mi>y</mml:mi> </mml:mrow> <mml:mi>A</mml:mi> </mml:msubsup> </mml:mrow> </mml:math> ) and longitudinal resistivity, exceeds 2 and increases monotonically from 3.16 to 4.46 as the film thickness increases, which may be associated with interfacial scattering.