Remarkably robust and correlated coherence and antiferromagnetism in (Ce\(_{1-x}\)La\(_x\))Cu\(_2\)Ge\(_2\)

• Published in: arXiv.org
• Main Authors: Hodovanets, H, Bud'ko, S L, Straszheim, W E, Taufour, V, Mun, E D, Kim, H, Flint, R, Canfield, P C
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 31.08.2015
• Subjects: Antiferromagnetism; Coherent scattering; Magnetic permeability; Percolation; Power measurement; Single crystals; Specific heat
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1412.2092

We present magnetic susceptibility, resistivity, specific heat, and thermoelectric power measurements on (Ce\(_{1-x}\)La\(_x\))Cu\(_2\)Ge\(_2\) single crystals (0 \(\leq x\leq\) 1). With La substitution, the antiferromagnetic temperature \(T_N\) is suppressed in an almost linear fashion and moves below 0.36 K, the base temperature of our measurements for \(x>\) 0.8. Surprisingly, in addition to robust antiferromagnetism, the system also shows low temperature coherent scattering below \(T_{coh}\) up to \(\sim\) 0.9 of La, indicating a small percolation limit \(\sim\) 9\(\%\) of Ce that separates a coherent regime from a single-ion Kondo impurity regime. \(T_{coh}\) as a function of magnetic field was found to have different behavior for \(x\)< 0.9 and \(x\)> 0.9. Remarkably, \((T_{coh})^2\) at \(H\) = 0 was found to be linearly proportional to \(T_N\). The jump in the magnetic specific heat \(\delta C_{m}\) at \(T_N\) as a function of \(T_K/T_N\) for (Ce\(_{1-x}\)La\(_x\))Cu\(_2\)Ge\(_2\) follows the theoretical prediction based on the molecular field calculation for the \(S\) = 1/2 resonant level model.