We present magnetic susceptibility, resistivity, specific heat, and thermoelectric power measurements on (Ce1-xLax)Cu2Ge2 single crystals (0 ≤ x ≤ 1). With La substitution, the antiferromagnetic temperature TN 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 Tcoh up to ∼0.9 of La, indicating a small percolation limit ∼9% of Ce. Tcoh as a function of magnetic field was found to have different behavior for x < 0.9 and x > 0.9. Remarkably, (Tcoh)2 at H = 0 was found to be linearly proportional to TN. The jump in the magnetic specific heat δCm at TN as a function of TK/TN for (Ce1-xLax)Cu2Ge2 follows the theoretical prediction based on the molecular field calculation for the S = 1/2 resonant level model.
H. Hodovanets et al., "Remarkably Robust and Correlated Coherence and Antiferromagnetism in (Ce₁₋ₓLaₓ)Cu₂Ge₂," Physical Review Letters, vol. 114, no. 23, article no. 236601, American Physical Society (APS), Jun 2015.
The definitive version is available at https://doi.org/10.1103/PhysRevLett.114.236601
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08 Jun 2015