Elucidating the lack of magnetic order in the heavy-fermion CeCu2Mg

作者：Michor H^*; Sereni J G; Giovannini M; Kampert E; Salamakha L; Hilscher G; Bauer E

来源：PHYSICAL REVIEW B, 2017, 95(11): 115146.

DOI：10.1103/PhysRevB.95.115146

Magnetic, transport, and thermal properties of CeCu2Mg are investigated to elucidate the lack of magnetic order in this heavy-fermion compound with a specific heat value, C-mag/T |(T -> 0) approximate to 1.2 J/mol K-2 and robust effective magnetic moments (mu(eff) approximate to 2.46 mu(B)). The lack of magnetic order is attributed to magnetic frustration favored by the hexagonal configuration of the Ce sublattice. In fact, the effect of magnetic field on C-mag/T and residual resistivity rho(0) does not correspond to that of a Fermi liquid (FL) because a broad anomaly appears at T-max approximate to 1.2 K in C-mag(T)/T, without changing its position up to mu H-0 = 7.5 T. However, the flattening of C-mag/T |(T -> 0) and its magnetic susceptibility chi T -> 0, together with the T-2 dependence of rho(T), reveal a FL behavior for T <= 2 K which is also supported by Wilson and Kadowaki-Woods ratios. The unusual coexistence of FL and frustration phenomena can be understood by placing paramagnetic CeCu2Mg in an intermediate section of a frustration-Kondo model. The entropy, S-mag, reaches 0.87 R ln 6 at T similar or equal to 100 K, with a tendency to approach the expected value S-mag = R ln 6 of the J = 5/2 ground state of Ce3+.

• 出版日期2017-3-27