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Charge density waves and soft phonon evolution in the superconductor BaNi2(As1−xPx)2

Tom Lacmann1, Sofia-Michaela Souliou1, Fabian Henssler1, Mehdi Frachet1, Philippa Helen McGuinness1, Michael Merz1,2, Björn Wehinger3, Daniel A. Chaney3, Amir-Abbas Haghighirad1 et al.

Rolf Heid1 and Matthieu Le Tacon1,*

  • *Contact author: Matthieu.LeTacon@kit.edu
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Phys. Rev. B 112, 054101 – Published 4 August, 2025

DOI: https://doi.org/10.1103/cj6x-jtr3

Abstract

The superconductor BaNi2As2 exhibits a soft-phonon-driven, incommensurate charge density wave (I-CDW) which is accompanied by a small orthorhombic structural phase transition. Upon further cooling, BaNi2As2 undergoes a first-order structural transition to a triclinic phase in which a commensurate CDW (C-CDW) appears. The relationship and interplay between the I-CDW, C-CDW and structural phase transitions have remained elusive. To investigate this issue, we present a complementary study of thermal diffuse x-ray scattering and inelastic x-ray scattering for phosphorus substituted BaNi2(As1−xPx)2(x≲0.12) and down to 2.2K. We show that most of the diffuse scattering signal can be well described by first-principles lattice dynamics calculations. Furthermore, we find that although phosphorus substitution rapidly suppresses the structural transition temperatures, the temperature dependence of the correlation length of the I-CDW fluctuations and the formation of Bragg-like superstructure peaks associated with long-range ordering of this order depends only weakly on the substitution level. Finally, we present the absence of signatures of the I-CDW to C-CDW or triclinic transition in the lattice dynamics, indicating that these instabilities are not (soft) phonon driven.

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References (43)

  1. P. Gegenwart, Q. Si, and F. Steglich, Quantum criticality in heavy-fermion metals, Nat. Phys. 4, 186 (2008).
  2. G. R. Stewart, Superconductivity in iron compounds, Rev. Mod. Phys. 83, 1589 (2011).
  3. B. Keimer, S. A. Kivelson, M. R. Norman, S. Uchida, and J. Zaanen, From quantum matter to high-temperature superconductivity in copper oxides, Nature (London) 518, 179 (2015).
  4. D. Fay and J. Appel, Coexistence of p-state superconductivity and itinerant ferromagnetism, Phys. Rev. B 22, 3173 (1980).
  5. R. M. Fernandes, A. V. Chubukov, and J. Schmalian, What drives nematic order in iron-based superconductors? Nat. Phys. 10, 97 (2014).
  6. S. Nandi, M. G. Kim, A. Kreyssig, R. M. Fernandes, D. K. Pratt, A. Thaler, N. Ni, S. L. Bud'ko, P. C. Canfield, J. Schmalian, R. J. McQueeney, and A. I. Goldman, Anomalous suppression of the orthorhombic lattice distortion in superconducting Ba(Fe1−xCox)2As2 single crystals, Phys. Rev. Lett. 104, 057006 (2010).
  7. M. Rotter, M. Tegel, D. Johrendt, I. Schellenberg, W. Hermes, and R. Pöttgen, Spin-density-wave anomaly at 140 K in the ternary iron arsenide BaFe2As2, Phys. Rev. B 78, 020503(R) (2008).
  8. A. E. Böhmer, P. Burger, F. Hardy, T. Wolf, P. Schweiss, R. Fromknecht, H. v. Löhneysen, C. Meingast, H. K. Mak, R. Lortz, S. Kasahara, T. Terashima, T. Shibauchi, and Y. Matsuda, Thermodynamic phase diagram, phase competition, and uniaxial pressure effects in BaFe2(As1−xPx)2 studied by thermal expansion, Phys. Rev. B 86, 094521 (2012).
  9. F. Hardy, P. Burger, T. Wolf, R. A. Fisher, P. Schweiss, P. Adelmann, R. Heid, R. Fromknecht, R. Eder, D. Ernst, H. v. Löhneysen, and C. Meingast, Doping evolution of superconducting gaps and electronic densities of states in Ba(Fe1−xCox)2As2 iron pnictides, Europhys. Lett. 91, 47008 (2010).
  10. S. Avci, O. Chmaissem, D. Y. Chung, S. Rosenkranz, E. A. Goremychkin, J. P. Castellan, I. S. Todorov, J. A. Schlueter, H. Claus, A. Daoud-Aladine, D. D. Khalyavin, M. G. Kanatzidis, and R. Osborn, Phase diagram of Ba1−xKxFe2As2, Phys. Rev. B 85, 184507 (2012).
  11. T. Yamazaki, N. Takeshita, R. Kobayashi, H. Fukazawa, Y. Kohori, K. Kihou, C.-H. Lee, H. Kito, A. Iyo, and H. Eisaki, Appearance of pressure-induced superconductivity in BaFe2As2 under hydrostatic conditions and its extremely high sensitivity to uniaxial stress, Phys. Rev. B 81, 224511 (2010).
  12. M. Pfisterer and G. Nagorsen, Zur struktur ternärer Übergangsmetallarsenide, Z. Naturforschung B 35, 703 (1980).
  13. F. Ronning, N. Kurita, E. D. Bauer, B. L. Scott, T. Park, T. Klimczuk, R. Movshovich, and J. D. Thompson, The first order phase transition and superconductivity in BaNi2As2 single crystals, J. Phys.: Condens. Matter 20, 342203 (2008).
  14. S. Lee, G. de la Peña, S. X.-L. Sun, M. Mitrano, Y. Fang, H. Jang, J.-S. Lee, C. Eckberg, D. Campbell, J. Collini, J. Paglione, F. M. F. de Groot, and P. Abbamonte, Unconventional charge density wave order in the pnictide superconductor Ba(Ni1−xCox)2As2, Phys. Rev. Lett. 122, 147601 (2019).
  15. C. Eckberg, D. J. Campbell, T. Metz, J. Collini, H. Hodovanets, T. Drye, P. Zavalij, M. H. Christensen, R. M. Fernandes, S. Lee, P. Abbamonte, J. W. Lynn, and J. Paglione, Sixfold enhancement of superconductivity in a tunable electronic nematic system, Nat. Phys. 16, 346 (2020).
  16. M. Merz, L. Wang, T. Wolf, P. Nagel, C. Meingast, and S. Schuppler, 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, Phys. Rev. B 104, 184509 (2021).
  17. S. M. Souliou, T. Lacmann, R. Heid, C. Meingast, M. Frachet, L. Paolasini, A.-A. Haghighirad, M. Merz, A. Bosak, and M. Le Tacon, Soft-phonon and charge-density-wave formation in nematic BaNi2As2, Phys. Rev. Lett. 129, 247602 (2022).
  18. Y. Song, S. Wu, X. Chen, Y. He, H. Uchiyama, B. Li, S. Cao, J. Guo, G. Cao, and R. Birgeneau, Phonon softening and slowing-down of charge density wave fluctuations in BaNi2As2, Phys. Rev. B 107, L041113 (2023).
  19. A. S. Sefat, M. A. McGuire, R. Jin, B. C. Sales, D. Mandrus, F. Ronning, E. D. Bauer, and Y. Mozharivskyj, Structure and anisotropic properties of BaFe2−xNixAs2 (x=0, 1, and 2) single crystals, Phys. Rev. B 79, 094508 (2009).
  20. T. Lacmann, A.-A. Haghighirad, S.-M. Souliou, M. Merz, G. Garbarino, K. Glazyrin, R. Heid, and M. Le Tacon, High-pressure phase diagram of BaNi2As2: Unconventional charge density waves and structural phase transitions, Phys. Rev. B 108, 224115 (2023).
  21. K. Kudo, M. Takasuga, Y. Okamoto, Z. Hiroi, and M. Nohara, Giant phonon softening and enhancement of superconductivity by phosphorus doping of BaNi2As2, Phys. Rev. Lett. 109, 097002 (2012).
  22. C. Meingast, A. Shukla, L. Wang, R. Heid, F. Hardy, M. Frachet, K. Willa, T. Lacmann, M. Le Tacon, M. Merz, A.-A. Haghighirad, and T. Wolf, Charge density wave transitions, soft phonon, and possible electronic nematicity in BaNi2(As1−xPx)2, Phys. Rev. B 106, 144507 (2022).
  23. M. Frachet, P. Wiecki, T. Lacmann, S. M. Souliou, K. Willa, C. Meingast, M. Merz, A.-A. Haghighirad, M. Le Tacon, and A. E. Böhmer, Elastoresistivity in the incommensurate charge density wave phase of BaNi2(As1−xPx)2, npj Quantum Mater. 7, 115 (2022).
  24. F. Henssler, K. Willa, M. Frachet, T. Lacmann, D. A. Chaney, R. Heid, M. Merz, A.-A. Haghighirad, and M. Le Tacon, Impact of Ca substitution on competing orders in superconducting BaNi2As2, Phys. Rev. Mater. 9, 044801 (2025).
  25. K. Kudo, M. Takasuga, and M. Nohara, Copper doping of BaNi2As2: Giant phonon softening and superconductivity enhancement, arXiv:1704.04854.
  26. Y. Yao, R. Willa, T. Lacmann, S.-M. Souliou, M. Frachet, K. Willa, M. Merz, F. Weber, C. Meingast, R. Heid, A.-A. Haghighirad, J. Schmalian, and M. Le Tacon, An electronic nematic liquid in BaNi2As2, Nat. Commun. 13, 4535 (2022).
  27. M. Krisch and F. Sette, Inelastic x-ray scattering from phonons, in Light Scattering in Solid IX, edited by M. Cardona and R. Merlin (Springer Berlin Heidelberg, Berlin, Heidelberg, 2007), pp. 317–370.
  28. A. Girard, T. Nguyen-Thanh, S. M. Souliou, M. Stekiel, W. Morgenroth, L. Paolasini, A. Minelli, D. Gambetti, B. Winkler, and A. Bosak, A new diffractometer for diffuse scattering studies on the ID28 beamline at the ESRF, J. Synchrotron Radiat. 26, 272 (2019).
  29. Rigaku Oxford Diffraction Ltd, Yarnton, Oxfordshire, E 2015 CrysAlis PRO (2015), https://rigaku.com/products/crystallography/x-ray-diffraction/crysalispro.
  30. See Supplemental Material at http://link.aps.org/supplemental/10.1103/cj6x-jtr3 for information on the samples, additional reciprocal space maps, linecuts, fit parameters, IXS spectra around the superconducting transition and in the longitudinal direction, and a discussion of the indications of phonon softening around the position of a second I-CDW emerging under hydrostatic pressure.
  31. B. Wehinger, A. Bosak, G. Piccolboni, K. Refson, D. Chernyshov, A. Ivanov, A. Rumiantsev, and M. Krisch, Diffuse scattering in metallic tin polymorphs, J. Phys.: Condens. Matter 26, 115401 (2014).
  32. A. Mirone and B. Wehinger, ab2tds, version 1.1, European Synchrotron Radiation Facility, https://gitlab.esrf.fr/mirone/ab2tds.
  33. C. F. Eagen, S. A. Werner, and R. B. Saillant, Amplitude and nature of the charge-density-wave displacements in K2Pt(CN)4Br0.3.3.2D2O (KCP) at low temperatures, Phys. Rev. B 12, 2036 (1975).
  34. C. Song, J. Park, J. Koo, K.-B. Lee, J. Y. Rhee, S. L. Bud'ko, P. C. Canfield, B. N. Harmon, and A. I. Goldman, Charge-density-wave orderings in LaAgSb2: An x-ray scattering study, Phys. Rev. B 68, 035113 (2003).
  35. A. Bosak, S.-M. Souliou, C. Faugeras, R. Heid, M. R. Molas, R.-Y. Chen, N.-L. Wang, M. Potemski, and M. Le Tacon, Evidence for nesting-driven charge density wave instabilities in the quasi-two-dimensional material LaAgSb2, Phys. Rev. Res. 3, 033020 (2021).
  36. A. R. Pokharel, V. Grigorev, A. Mejas, T. Dong, A. A. Haghighirad, R. Heid, Y. Yao, M. Merz, M. Le Tacon, and J. Demsar, Dynamics of collective modes in an unconventional charge density wave system BaNi2As2, Commun. Phys. 5, 141 (2022).
  37. Y. Chen, N. Giles-Donovan, J. Guo, R. Chen, H. Fukui, T. Manjo, D. Ishikawa, A. Q. R. Baron, Y. Song, and R. J. Birgeneau, Charge density fluctuations with enhanced superconductivity at the proposed nematic quantum critical point, arXiv:2410.03956.
  38. G. Ghiringhelli, M. L. Tacon, M. Minola, S. Blanco-Canosa, C. Mazzoli, N. B. Brookes, G. M. D. Luca, A. Frano, D. G. Hawthorn, F. He, T. Loew, M. M. Sala, D. C. Peets, M. Salluzzo, E. Schierle, R. Sutarto, G. A. Sawatzky, E. Weschke, B. Keimer, and L. Braicovich, Long-range incommensurate charge fluctuations in (Y,Nd)Ba2Cu3O6+x, Science 337, 821 (2012).
  39. J. Chang, E. Blackburn, A. T. Holmes, N. B. Christensen, J. Larsen, J. Mesot, R. Liang, D. A. Bonn, W. N. Hardy, A. Watenphul, M. v. Zimmermann, E. M. Forgan, and S. M. Hayden, Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3O6.67, Nat. Phys. 8, 871 (2012).
  40. I. Vinograd, S. M. Souliou, A.-A. Haghighirad, T. Lacmann, Y. Caplan, M. Frachet, M. Merz, G. Garbarino, Y. Liu, S. Nakata, K. Ishida, H. M. L. Noad, M. Minola, B. Keimer, D. Orgad, C. W. Hicks, and M. Le Tacon, Using strain to uncover the interplay between two- and three-dimensional charge density waves in high-temperature superconducting YBa2Cu3Oy, Nat. Commun. 15, 3277 (2024).
  41. M. Leroux, V. Mishra, C. Opagiste, P. Rodière, A. Kayani, W.-K. Kwok, and U. Welp, Charge density wave and superconductivity competition in Lu5Ir4Si10: A proton irradiation study, Phys. Rev. B 102, 094519 (2020).
  42. F. Stier, A.-A. Haghighirad, G. Garbarino, S. Mishra, N. Stilkerich, D. Chen, C. Shekhar, T. Lacmann, C. Felser, T. Ritschel, J. Geck, and M. Le Tacon, Pressure-dependent electronic superlattice in the kagome superconductor CsV3Sb5, Phys. Rev. Lett. 133, 236503 (2024).
  43. T. Lacmann, S.-M. Souliou, F. Henssler, M. Frachet, P. H. McGuinness, D. A. Chaney, and M. Le Tacon, “Charge density waves and soft phonon evolution in the superconductor BaNi2(As1−xPx)2 (2025)” [DataSet], https://dx.doi.org/10.35097/485k5eg675xf4c6d.

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Phys. Rev. B 112, 054101– Published 4 August, 2025
  • Received 16 May 2025
  • Accepted 18 July 2025
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