Remarkably Robust and Correlated Coherence and Antiferromagnetism in (Ce1-xLax)Cu2Ge2
Straszheim, W. E.
Mun, E. D.
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.
This article is published as Hodovanets, H., S. L. Bud’ko, W. E. Straszheim, V. Taufour, E. D. Mun, H. Kim, R. Flint, and P. C. Canfield. "Remarkably Robust and Correlated Coherence and Antiferromagnetism in (Ce 1− x La x) Cu 2 Ge 2." Physical Review Letters 114, no. 23 (2015): 236601. DOI: 10.1103/PhysRevLett.114.236601. Posted with permission.