Single-crystal study of the charge density wave metal LuNiC2

Abstract

We report on single crystal growth, single crystal x-ray diffraction, physical properties and density functional theory (DFT) electronic structure as well as Fermi surface calculations for two ternary carbides, LuCoC2 and LuNiC2. Electrical resistivity measurements reveal for LuNiC2 a charge density wave (CDW) transition at TCDW 450 K and, for T > TCDW, a significant anisotropy of the electrical resistivity, which is lowest along the orthorhombic a-axis. The analysis of x-ray superstructure reflections suggest a commensurate CDW state with a Peierls-type distortion of the Ni atom periodicity along the orthorhombic a-axis. DFT calculations based on the CDW modulated monoclinic structure model of LuNiC2 as compared to results of the orthorhombic parent-type reveal the formation of a partial CDW gap at the Fermi level which reduces the electronic density of states from N (EF) = 1.03 states/eV f.u. without CDW to N (EF) = 0.46 states/eV f.u. in the CDW state. The corresponding bare DFT Sommerfeld value of the latter, γ CDW DFT = 0.90 mJ/mol K 2 , reaches reasonable agreement with the experimental value γ = 0.83(5) mJ/mol K 2 of LuNiC2. LuCoC2 displays a simple metallic behavior with neither CDW ordering nor superconductivity above 0.4 K. Its experimental Sommerfeld coefficient, γ = 5.9(1) mJ/mol K 2 , is in realistic correspondence with the calculated, bare Sommerfeld coefficient, γDFT = 3.82 mJ/mol K 2 , of orthorhombic LuCoC2.

Anisotropic and extreme magnetoresistance in the magnetic semimetal candidate erbium monobismuthide

“…2(a) shows the specific heat of LuBi in temperature range from 2 to 20 K and its fit (the red line) with the expression C P = γ T + βT 3 [38], from which the Sommerfeld coefficient γ is determined as 0.3 mJ/K 2 mol, being of the same order of magnitude as for LaBi (0.85 mJ/K 2 mol) [39] and β has a value of 1.2 mJ/K 4 mol. Generally, the lattice contribution can be simply understood by the Debye model with the temperature-independent Debye temperature D [40]. The value of D = 171.2 K for ErBi is obtained using this relation: [40], where M is the molar mass and LaBi D = 178 K is taken from Ref.…”

“…Generally, the lattice contribution can be simply understood by the Debye model with the temperature-independent Debye temperature D [40]. The value of D = 171.2 K for ErBi is obtained using this relation: [40], where M is the molar mass and LaBi D = 178 K is taken from Ref. [41].…”

“…And, it can also be seen that larger electronic density of states at the Fermi level N (E F ) occurs in ErBi, since the electronic density of states is related to the Sommerfeld coefficient through N (E F ) = 3γ /k 2 B π 2 [40]. To better understand the functional dependence of the low-temperature magnetic contribution to the specific heat, we fit the data below 3.5 K with C m ∼ AT 3 e −E g/T which is expected to work in an antiferromagnet with an energy gap E g in the magnon dispersion relation [42].…”

Pressure influence on the valence and magnetic state of Yb ions in noncentrosymmetric heavy-fermion YbNiC2

“…Inset: Full heat capacity. ciated with β HT as β HT = 12π 4 /5nR 3 D is D = 413 K. From a comparison with the specific heat of LuNiC 2 [36], the main part of the specific heat of YbNiC 2 below 40 K stems from 4 f contribution as in the case of RNiC 2 with R = Ho, Er, Dy [51]. It may be attributed to the Schottky part of (2J + 1)-multiplet split in the crystal field.…”

“…The family of NC carbides RNiC 2 (where R is a rareearth element) is studied intensively. The many nontrivial phenomena have been observed in them, such as quantum critical behavior, interplay of charge density wave (CDW), magnetism, and unconventional superconductivity [30][31][32][33][34][35][36][37][38]. The compounds with R = Nd, Tb, Dy, Ho, Er, and Tm order antiferromagnetically at low temperatures [39,40].…”