Chemical pressure tuning of competing orders in ${\text{Ba}}_{1-x}{\text{Ca}}_x{\text{Ni}}_2{\text{As}}_2$

Abstract

$\mathrm{Ba}{\mathrm{Ni}}_2{\mathrm{As}}_2$, a structural-analogue to the iron-based parent compound $\mathrm{Ba}{\mathrm{Fe}}_2{\mathrm{As}}_2$, offers a unique platform to study the interplay between superconductivity, charge density waves and, possibly, electronic nematicity. Here, we report on the growth and characterization of ${\mathrm{Ba}}_{1-x}{\mathrm{Ca}}_x{\mathrm{Ni}}_2{\mathrm{As}}_2$ single crystals with $0\le x\le 0.1$, using a combination of x-ray diffraction, diffuse x-ray scattering, heat capacity, and electronic transport measurements. Our results demonstrate that calcium substitution affects the structural, electronic and thermodynamic properties of $\mathrm{Ba}{\mathrm{Ni}}_2{\mathrm{As}}_2$ in a way that is strongly reminiscent of moderate hydrostatic pressures albeit with marked differences. In particular Ca-substitution efficiently suppresses both the triclinic structural transition and the associated commensurate charge density wave formation, while increasing the superconducting transition temperature. We found that the substitution range in which the crystals remain homogeneous is limited as for concentrations $x\ge 0.04$ intense diffuse x-ray scattering indicates the formation of stacking faults, which, despite the preserved integrity of the NiAs layers, prevents investigation up to concentrations at which the chemical pressure would completely suppress the structural instability.

9 pages, 7 figures, 2 tables

References in corpus (17)

• Pressure-induced volume-collapsed tetragonal phase of CaFe2As2 as seen via neutron scattering
• First Order Phase Transition and Superconductivity in BaNi2As2 Single Crystals
• Structure and Anisotropic Properties of BaFe2-xNixAs2 (x = 0, 1, 2) Single Crystals
• Density functional study of BaNi${}_2$As${}_2$: Electronic structure, phonons and electron-phonon superconductivity
• Giant Phonon Softening and Enhancement of Superconductivity by Phosphorus Doping of BaNi2As2
• Multiple charge density waves and superconductivity nucleation at antiphase domain walls in the nematic pnictide Ba${}_{1-x}$Sr${}_x$Ni${}_2$As${}_2$
• An Electronic Nematic Liquid in BaNi${}_2$As${}_2$
• Elastoresistivity in the incommensurate charge density wave phase of BaNi${}_{\text{2}}$(As${}_{\text{1-x}}$P${}_{\text{x}}$)${}_{\text{2}}$
• Soft-phonon and charge-density-wave formation in nematic BaNi${}_2$As${}_2$
• Rotational symmetry breaking at the incommensurate charge-density-wave transition in Ba(Ni,Co)${}_2$(As,P)${}_2$: Possible nematic phase induced by charge/orbital fluctuations
• Phonon softening and slowing down of charge-density-wave fluctuations in BaNi${}_2$As${}_2$
• Vortex-lattice melting and paramagnetic depairing in the nematic superconductor FeSe
• Potential Lifshitz transition at optimal substitution in nematic pnictide Ba${}_{1-x}$Sr${}_x$Ni${}_2$As${}_2$
• The high-pressure phase diagram of BaNi${}_2$As${}_2$: unconventional charge-density-waves and structural phase transitions
• Slope of the upper critical field at $T_c$ in two-band superconductors with non-magnetic disorder: $s_{++}$ superconductivity in ${\text{Ba}}_{1-x}{\text{K}}_x{\text{Fe}}_2{\text{As}}_2$
• Strong electron-phonon coupling in Ba${}_{1-x}$Sr${}_x$Ni${}_2$As${}_2$
• Charge Order Evolution of Superconducting BaNi2As2 Under High Pressure

Cited by in corpus (2)

• Charge density waves and soft phonon evolution in the superconductor BaNi${}_2$(As${}_{1-x}$P${}_x$)${}_2$
• Orbital Ordering in the Charge Density Wave Phases of BaNi${}_2$(As${}_{1-x}$P${}_x$)${}_2$