Tuning the ferromagnetic phase in the CDW compound SmNiC2 via chemical alloying

Abstract

We report a study on tuning the charge density wave (CDW) ferromagnet SmNiC2 to a weakly coupled superconductor by substituting La for Sm. X-ray diffraction measurements show that the doped compounds obey Vegard’s law, where La (Lu) alloying expands (shrinks) the lattice due to its larger (smaller) atomic size than Sm. In the series Sm1−xLaxNiC2, CDW transition (TCDW = 148 K) for SmNiC2 is gradually suppressed, while the ferromagnetic (FM) ordering temperature (TC) at 17 K slightly increases up to x = 0.3. For x > 0.3, TC starts to decrease and there is no signature that could be related with the CDW phase. Electrical resistivity, magnetic susceptibility and specific heat measurements point toward the possible presence of a FM quantum critical point (QCP) near x = 0.92, where the TC is extrapolated to zero temperature. Superconductivity in LaNiC2 (Tsc = 2.9 K) is completely suppressed with small amount of Sm inclusion near the proposed FM critical point, indicating a competition between the two ordered phases. The tunable lattice parameters via chemical substitution (La,Lu) and the ensuing change among the ordered phases of ferromagnetism, CDW and superconductivity underscores that SmNiC2 provides a rich avenue to study the rare example of a FM QCP, where the broken symmetries are intricately correlated.

Crossover from charge density wave stabilized antiferromagnetism to superconductivity in Nd1−xLaxNiC2 compounds

“…The difference between them is likely associated with a weakening of the AFM interactions and an increase of spin disorder. This behavior differs from the results obtained for Sm 1−x La x NiC 2 41 , and SmNiC 2−x B x 40 , where weak doping initially causes a slight increase of Curie temperature T C followed by more abrupt suppression of FM for higher doping rates.…”

“…1b)). The lattice parameters determined from the LeBail fit for the whole Nd 1−x La x NiC 2 series and for parent compounds NdNiC 2 and LaNiC 2 are in good agreement with previous reports 27,41 . As it is depicted in Fig.…”

“…The effect of pressure can be studied equivalently by applying external force or via chemical alloying, causing a change in the lattice parameters (increase or decrease, depending on the difference in atom size). The emergence of a ferromagnetic quantum criticality was previously suggested in SmNiC 2 studied under pressure 39 , SmNiC 2−x B x 40 , and Sm 1−x La x NiC 2 solid solution 41,42 . So far, the aniferromagnetic QCP in this family have been revealed under hydrostatic pressure in LaNiC 2 25 and CeNiC 2 43 .…”

Magnetism and charge density waves inRNiC2(R=Ce,Pr,Nd)

“…Alternatively, a constructive effect has been observed in a group of materials, in which this FS transformation leads to the enhancement of the nesting conditions or when the nesting vector has the ability to adapt to the evolution of the Fermi surface [9][10][11][12][13][14][15] . Recently, much attention of the researchers exploring the coupling between CDW, superconductivity and magnetic order has been devoted to the two families of ternary compounds: M 5 Ir 4 Si 10 , (where M = Y, Dy, Ho, Er, Tm, Yb or Lu ) [16][17][18][19][20][21][22][23][24] and RNiC 2 , (where R = La, Ce, Pr, Nd, Sm, Gd or Tb) 25,26 . Most of the members of the latter family exhibit the Peierls transitions towards the charge density wave state 27 .…”

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

“…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].…”