Complex magnetic states of the heavy fermion compound CeGe

Abstract

The intermetallic compound CeGe exhibits unusual magnetic behavior due to the interplay between the Kondo and the antiferromagnetic coupling. This particular system is interesting because the Kondo temperature is close to the Néel temperature, resulting in a close competition between the low-temperature interactions, which can be tuned by means of varying external parameters such as pressure and applied magnetic field. Interestingly, magnetization measurements up to 12 kbar reveal that the Néel temperature is not affected by pressure. Measurements of the electrical resistivity, however, show that the sharp upturn appearing below T N is sensitive to pressures up to 15 kbar. This suggests that pressure may change the complex antiferromagnetic spin structure. The validity of an explanation based on the magnetic superzones seen in the rare earths is discussed here. PACS: 71.27.+a Strongly correlated electron systems; heavy fermions; 75.50.-y Studies of specific magnetic materials; 75.50.Ee Antiferromagnetics.

Possibility of a new order parameter driven by multipolar moment and Fermi surface evolution in CeGe

“…The negative value of θ p indicates to the dominance of antiferromagnetic interactions. Thus, it can be said that the peak around T I arises due to the antiferromagnetic ordering which is also consistent with the observed shifting of T I down in temperature, above 1 T. The presence of antiferromagnetic ordering around T I is in accordance to literature reports 15 , 16 , however, there are no reports about the second peak which is observed at low fields. In order to collect further information, the magnetic field response of isothermal magnetization ( M ) curves at different temperatures is measured (as shown in Fig.…”

“…In this context, CeGe is an interesting 4f electron based system though; there are only few literature reports about this compound. This indicates that the magnetic state of this compound is quite complex [13][14][15][16][17]. Recent studies on single crystals of CeGe report the presence of magnetic anisotropy as well as gap opening [16].…”

A Canonical Transformation for the Anderson Lattice Hamiltonian with f–f Electron Coupling

“…When rare-earth or actinide atoms constitute a sublattice in a compound, the system may be called Kondo lattice compound. The examples may include CeAl 3 [8][9][10], CeCu 2 Si 2 [11][12][13], UBe 13 [14][15][16], CeB 6 [17,18], CeCu 6 [19][20][21], CePtSi [22], Ce 2 PdIn 8 [23], CeGe [24], (Ce 1−x La x )Cu 2 Ge 2 [25], Yb 3 Ru 4 Al 12 [26], UAuBi 2 [27], Ce(Cu, Al,Si) 2 [28], CeCu 2 Mg [29], Ce 2 Rh 3 Sn 5 [30], CeRhIn 5 [31], CeCu 9 In 2 [32], and others. Doniach [33] studied a one-dimensional Kondo lattice model for Kondo lattice compound and suggested that a second-order transition from an antiferromagnetic state to a Kondo spin compensated ground state could occur as the exchange coupling constant J increased to a critical value J c ; for systems in which J ∼ J c , a very weak sublattice magnetization may occur as a result of nearly complete spin-compensation.…”