Fermi surface inLaRhSi3andCeRhSi3

Abstract

We report on de Haas-van Alphen ͑dHvA͒ effect measurements at ambient pressure and band-structure calculations for LaRhSi 3 and CeRhSi 3 , whose crystal structures lack space-inversion symmetry. For LaRhSi 3 , dHvA frequencies up to ϳ11 kT with effective masses up to ϳ1.6m e , where m e is the free-electron mass, are observed. The observed and the calculated Fermi surfaces are in satisfactory quantitative agreement. The energy splitting of bands due to the spin-orbit coupling is estimated to be of the order of 10 2 K. For CeRhSi 3 , dHvA frequencies up to ϳ12 kT with effective masses up to ϳ19m e are observed. The dHvA frequency branches are definitely different from those observed in LaRhSi 3 and are difficult to explain with the LaRhSi 3 Fermi surface. This leads to the conclusion that the Ce 4f electrons in CeRhSi 3 are itinerant in the antiferromagnetic state at ambient pressure. The Fermi surface resulting from a band-structure calculation in which the Ce 4f electrons are treated as itinerant can provide a plausible explanation for the observed frequency branches, although the quantitative agreement is rather limited. The comparison of the calculated density of states with the Sommerfeld coefficient gives the mass enhancement factor of 8.

Existence of Majorana Fermions and Topological Order in Nodal Superconductors with Spin-Orbit Interactions in External Magnetic Fields

“…The dependence of the conductance on the parity of vorticity inside the superconductor signifies clearly the MF contributions [34,35]. Possible candidates of our proposal are heavy fermion NCS superconductors CeRhSi 3 and CeIrSi 3 , in which the Fermi level is close to time-reversal invariant k points at K points in the BZ [20,21,24]. Although there are two K points, one of them can be moved away from the Fermi level by applying an uniaxial strain in the x (or y) direction.…”

“…Note that many classes of noncentrosymmetric (NCS) superconductors, such as CePt 3 Si, CeRhSi 3 , CeIrSi 3 , and Li 2 Pt 3 B, are known to possess superconducting gap nodes [19][20][21][22][23]. In these systems, some of timereversal invariant k points reside close to the Fermi level [24]. Our finding indicates that if the total number of these k points is odd, and the superconducting gap vanishes (or, at least, becomes sufficiently small) at these points, stable MF modes appear under applied magnetic fields.…”

Spin Density Wave Ordering in CeIrSi3

“…[1][2][3][4][5][6][7][8] It is also pointed out that both of them lie close to the quantum critical point, and interestingly Ce 4f electrons are itinerant even in their antiferromagnetic phase in sharp contrast to CeRhIn 5 in which Ce 4f electrons are localized in the antiferromagnetic phase. 9) The itinerant character of the Ce 4f electron in CeRhSi 3 was pointed out by de Haas-van Alphen (dHvA) measurements.…”

“…9) The itinerant character of the Ce 4f electron in CeRhSi 3 was pointed out by de Haas-van Alphen (dHvA) measurements. 2,4,5) When Ce 4f electrons are localized, the Fermi surfaces (FSs) in CeRhSi 3 will be very similar to those in LaRhSi 3 . On the other hand, the observed dHvA frequencies and then FSs in CeRhSi 3 are totally different to those in LaRhSi 3 , and these results are interpreted as a strong indication of the itinerant character of Ce 4f electrons in CeRhSi 3 .…”

Magnetoelectric effect and the upper critical field in superconductors without inversion center

“…An important property of the Fermi surfaces (13) is the fact that their shapes depend on the magnetic field in a characteristic way, which can be directly probed by dHvA experiments [22,23]. Note that while at = 0 H time reversal symmetry guarantees ( ) = ( ) λ λ ξ ξ −k k , the loss of time reversal symmetry for 0…”