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The antiferromagnetic phase transition of the heavy-fermion system Ce(Cu<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub></semantics></math></inline-formula>Co<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>x</mi></msub></semantics></math></inline-formula>)<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>Ge<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula> for <i>x</i> = 0.05 and 0.2, showing up in specific heat, magnetic susceptibility, and muon spin relaxation (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>μ</mi></semantics></math></inline-formula>SR) data, has been further investigated. The neutron diffraction (ND) results show that Co-doping drastically reduces the moment size of Ce, without a qualitative change in the magnetic structure of the undoped compound CeCu<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>Ge<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>. An incommensurate magnetic propagation vector <i>k</i> = (0.2852, 0.2852, 0.4495) with a cycloidal magnetic structure with a Ce moment of 0.55 <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>μ</mi><mi mathvariant="normal">B</mi></msub></semantics></math></inline-formula> in the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>a</mi><mi>b</mi></mrow></semantics></math></inline-formula>-plane has been observed for <i>x</i> = 0.05. Although for <i>x</i> = 0.2 the specific heat and magnetic susceptibility data reflect a phase transition with a broad peak and the muon relaxation rate shows a sharp peak at <i>T</i> = 0.9 K, our ND data dismiss the possibility of a long-range magnetic ordering down to 50 mK. The ND data, along with previously reported results for <i>x</i> = 0.2, are interpreted in terms of the reduced ordered state magnetic moments of the Ce<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></semantics></math></inline-formula> ion by Kondo screening and the presence of dynamical short-range magnetic correlations.