Nesting Properties and Anisotropy of the Fermi Surface ofLuNi2B2C

Abstract

The rare earth nickel borocarbides, with the generic formula RNi2B2C, have recently been shown to display a rich variety of phenomena. Most striking has been the competition between, and even coexistence of, antiferromagnetism and superconductivity. We have measured the Fermi surface (FS) of LuNi2B2C, and shown that it possesses nesting features capable of explaining some of the phenomena experimentally observed. In particular, it had previously been conjectured that a particular sheet of FS is responsible for the modulated magnetic structures manifest in some of the series. We report the first direct experimental observation of this sheet.

Anisotropics-wave superconductivity in borocarbidesLuNi2B2CandMaki1, Thalmeier2, Won3 2002Phys. Rev. B

“…There is no symmetry reason why the amplitudes (or pair potentials) of inequivalent representations like s and g should be very close. However from the bandstructure of borocarbides 18 it may be argued that the pair potential at the nodal points given above is indeed strongly suppressed. The main Fermi surface sheet shows lobe like structures along the [110] directions which have strong nesting with a wave vector parallel to a.…”

Investigation of the superconducting energy gap in the compound LuNi2B2C by the method of point contact spectroscopy: two-gap approximation

“…1 According to electron structure calculation, ReNi 2 B 2 C compounds are three-dimensional metals in which all atoms contribute to the density of states at the Fermi surface. 2,3,4 In LuNi 2 B 2 C three energy bands crossing the Fermi level subdivide the Fermi surface into three distinct regions: (1) two spheroidal sheets at Γ-points that are extend along the c axis; (2) two flat P-centered square regions with the sides parallel to 100 and 010 , and finally (3) the largest basic X-centered part mostly cylindrical in shape (closely resembling practically twodimensional crystal structure) whose axis is parallel to the c axis. 2,3,4 In this sheet there are flat regions at the points 0.56±(2π/a), the nesting, typical for the compounds of this family.…”

“…2,3,4 In LuNi 2 B 2 C three energy bands crossing the Fermi level subdivide the Fermi surface into three distinct regions: (1) two spheroidal sheets at Γ-points that are extend along the c axis; (2) two flat P-centered square regions with the sides parallel to 100 and 010 , and finally (3) the largest basic X-centered part mostly cylindrical in shape (closely resembling practically twodimensional crystal structure) whose axis is parallel to the c axis. 2,3,4 In this sheet there are flat regions at the points 0.56±(2π/a), the nesting, typical for the compounds of this family. 4 It is precisely these features that determine the Kohn anomaly near the wave vector Q m ≈ (0.5, 0, 0) 5,6 and the incommensurate ordering with Q m ≈ (0.5, 0, 0) in AFM compounds.…”

Evolution of the Fermi surface and the oscillatory exchange coupling across Cr and Cr-based alloys

“…This well-established technique has recently been used by some of the present authors to determine the FS topology and identify nesting features in a wide range of systems. [21][22][23] The virtue of the 2D-ACAR technique in such studies is that it reveals directly the shape of the FS.…”