Pressure- and field-dependent behavior ofYbCu4Au

Strong Electronic Correlations in a New Yb-Based Compound: YbCu4Ni

“…This behaviour could be explained by the lifting of the degeneracy of the Yb crystalline electric field (CEF) ground--state doublet with increasing magnetic field, due to the Zeeman splitting. Correspondingly, the associated Schottky anomaly is shifted to higher temperatures, similarly to the case of the isotypic YbCu 4 Au [6]. Moreover, a small hump at 2.5 K, which is quenched in magnetic fields above 0.3 T, reflects a low amount of Yb 2 O 3 in the sample [7].…”

“…Moreover, a small hump at 2.5 K, which is quenched in magnetic fields above 0.3 T, reflects a low amount of Yb 2 O 3 in the sample [7]. The sharp anomaly at low applied magnetic field could be explained as possible indication of an expected antiferromagnetic phase transition below 0.5 K, similarly to the situation observed in YbCu 4 Au [6]. However, measurements in the millikelvin temperature range are required.…”

“…However, below these temperatures C/T begins to diverge to higher values which could be connected with a possible magnetic phase transition at T N . Similarly to the behaviour of YbCu 4 Au [6], the applied magnetic field should suppress T N . At 9 T we obtained by extrapolation γ = 370 mJ/(mol K 2 ), which is an indication of heavy fermion behaviour.…”

Ultrasonic Investigation of Quantum Criticality of the Polycrystal Compound YbAuCu4

“…[4][5][6][7][8][9][10][11] The Yb based face-centered-cubic series YbXCu 4 (X : transition metal) is one of the examples studied intensively in strongly correlated electron systems. [12][13][14][15][16][17][18][19][20] For instance, YbAgCu 4 is a prototypical HF compound that exhibits a linear Sommerfeld coefficient γ above 200 mJ/mol K 2 without any phase transition observed to the lowest temperatures measured. Furthermore, YbInCu 4 represents the most extreme limit of mixed-valence behavior.…”

“…[13][14] YbAuCu 4 show a specific heat peak below T N = 0.8 K, attributed to the occurrence of antiferromagnetic (AFM) phase transition. [12][13][14][15][16][17][18] Hence it is expected that hybridization is less important and that the crystalline electric field (CEF) energy levels of the Yb 3+ ion are well defined in YbAuCu 4 . In fact, the magnetic spectra corresponding to crystal field transitions have been observed by an inelastic neutron scattering measurement.…”