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Coexisting first- and second-order electronic phase transitions in a correlated oxide


The explanation and control of phase transitions remain cornerstones of contemporary physics. Landau provided an invaluable insight into the thermodynamics of complex systems by formulating their phase transitions in terms of an order parameter. Within this formulation, continuous evolution of the order parameter away from zero classifies the phase transition as second-order, whereas a discontinuous change signals a first-order transition. Here we show that the temperature-tuned insulator–metal transition in the prototypical correlated electron system NdNiO3 defies this established binary classification. By harnessing a nanoscale optical probe of the local electronic conductivity, we reveal two physically distinct yet concurrent phase transitions in epitaxial NdNiO3 films. Whereas the sample bulk exhibits a first-order transition between metal and insulator phases, we resolve anomalous nanoscale domain walls in the insulating state that undergo a distinctly continuous insulator–metal transition, with hallmarks of second-order behaviour. We ascribe these domain walls to boundaries between antiferromagnetically ordered domains within the charge ordered bulk. The close correspondence of these observations to predictions from a Landau theory of coupled charge and magnetic orders highlights the importance of coupled order parameters in driving the complex phase transition in NdNiO3.

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Fig. 1: Electronic phase separation and percolative phase transition in the NdNiO3 thin film revealed by nano-infrared imaging.
Fig. 2: Histogram representation of the percolative transition in NdNiO3 and Ising analysis.
Fig. 3: Metallic domain walls across the insulator–metal transition.
Fig. 4: Nano-infrared contrast across metal–insulator boundaries.


  1. 1.

    Dagotto, E. Complexity in strongly correlated electronic systems. Science 309, 257–262 (2005).

    ADS  Article  Google Scholar 

  2. 2.

    Imada, M., Fujimori, A. & Tokura, Y. Metal–insulator transitions. Rev. Mod. Phys. 70, 1039–1263 (1998).

    ADS  Article  Google Scholar 

  3. 3.

    Medarde, M. L. Structural, magnetic and electronic properties of perovskites (R=rare earth). J. Phys. Condens. Matter 9, 1679–1707 (1997).

    ADS  Article  Google Scholar 

  4. 4.

    Catalan, G. Progress in perovskite nickelate research. Phase Transit. 81, 729–749 (2008).

    Article  Google Scholar 

  5. 5.

    Hepting, M. et al. Tunable charge and spin order in PrNiO3 thin films and superlattices. Phys. Rev. Lett. 113, 227206 (2014).

    ADS  Article  Google Scholar 

  6. 6.

    Boris, A. V. et al. Dimensionality control of electronic phase transitions in nickel-oxide superlattices. Science 332, 937–940 (2011).

    ADS  Article  Google Scholar 

  7. 7.

    Basov, D. N., Averitt, R. D. & Hsieh, D. Towards properties on demand in quantum materials. Nat. Mater. 16, 1077–1088 (2017).

    ADS  Article  Google Scholar 

  8. 8.

    Stewart, M. K., Liu, J., Kareev, M., Chakhalian, J. & Basov, D. N. Mott physics near the insulator-to-metal transition in NdNiO3. Phys. Rev. Lett. 107, 176401 (2011).

    ADS  Article  Google Scholar 

  9. 9.

    Park, H., Millis, A. J. & Marianetti, C. A. Site-selective Mott transition in rare-earth-element nickelates. Phys. Rev. Lett. 109, 156402 (2012).

    ADS  Article  Google Scholar 

  10. 10.

    Johnston, S., Mukherjee, A., Elfimov, I., Berciu, M. & Sawatzky, G. A. Charge disproportionation without charge transfer in the rare-earth-element nickelates as a possible mechanism for the metal–insulator transition. Phys. Rev. Lett. 112, 106404 (2014).

    ADS  Article  Google Scholar 

  11. 11.

    Mandal, B. et al. The driving force for charge ordering in rare earth nickelates. Preprint at https://arXiv1701.06819 (2017).

  12. 12.

    Lee, S., Chen, R. & Balents, L. Landau theory of charge and spin ordering in the nickelates. Phys. Rev. Lett. 106, 016405 (2011).

    ADS  Article  Google Scholar 

  13. 13.

    Dhaka, R. S. et al. Tuning the metal–insulator transition in NdNiO3 heterostructures via Fermi surface instability and spin fluctuations. Phys. Rev. B 92, 035127 (2015).

    ADS  Article  Google Scholar 

  14. 14.

    Ruppen, J. et al. Optical spectroscopy and the nature of the insulating state of rare-earth nickelates. Phys. Rev. B 92, 155145 (2015).

    ADS  Article  Google Scholar 

  15. 15.

    McLeod, A. S. et al. Nanotextured phase coexistence in the correlated insulator V2O3. Nat. Phys. 13, 80–86 (2017).

    Article  Google Scholar 

  16. 16.

    Qazilbash, M. M. et al. Mott transition in VO2 revealed by infrared spectroscopy and nano-imaging. Science 318, 1750–1753 (2007).

    ADS  Article  Google Scholar 

  17. 17.

    Liu, M. K. et al. Anisotropic electronic state via spontaneous phase separation in strained vanadium dioxide films. Phys. Rev. Lett. 111, 096602 (2013).

    ADS  Article  Google Scholar 

  18. 18.

    Liu, M. et al. Symmetry breaking and geometric confinement in VO2: Results from a three-dimensional infrared nano-imaging. Appl. Phys. Lett. 104, 121905 (2014).

    ADS  Article  Google Scholar 

  19. 19.

    Atkin, J. M., Berweger, S., Jones, A. C. & Raschke, M. B. Nano-optical imaging and spectroscopy of order, phases, and domains in complex solids. Adv. Phys. 61, 745–842 (2012).

    ADS  Article  Google Scholar 

  20. 20.

    Liu, S. et al. Random field driven spatial complexity at the Mott transition in VO2. Phys. Rev. Lett. 116, 036401 (2016).

    ADS  Article  Google Scholar 

  21. 21.

    Phillabaum, B., Carlson, E. W. & Dahmen, K. A. Spatial complexity due to bulk electronic nematicity in a superconducting underdoped cuprate. Nat. Commun. 3, 915 (2012).

    ADS  Article  Google Scholar 

  22. 22.

    Aharony, A. & Stauffer, D. Introduction to Percolation Theory (Taylor & Francis, Abingdon, 2003).

  23. 23.

    Perković, O., Dahmen, K. & Sethna, J. P. Avalanches, Barkhausen noise, and plain old criticality. Phys. Rev. Lett. 75, 4528–4531 (1995).

    ADS  Article  Google Scholar 

  24. 24.

    Mattoni, G. et al. Striped nanoscale phase separation at the metal–insulator transition of heteroepitaxial nickelates. Nat. Commun. 7, 13141 (2016).

    ADS  Article  Google Scholar 

  25. 25.

    Sanati, M. & Saxena, A. Landau theory of domain walls for one-dimensional asymmetric potentials. Am. J. Phys. 71, 1005–1012 (2003).

    ADS  Article  Google Scholar 

  26. 26.

    Parks, R. D. Superconductivity: Part 1 (CRC, Boca Raton, 1969).

  27. 27.

    Torrance, J. B., Lacorre, P., Nazzal, A. I., Ansaldo, E. J. & Niedermayer, C. Systematic study of insulator–metal transitions in perovskites RNiO3 (R = Pr,Nd,Sm,Eu) due to closing of charge-transfer gap. Phys. Rev. B 45, 8209–8212 (1992).

    ADS  Article  Google Scholar 

  28. 28.

    Daraktchiev, M., Catalan, G. & Scott, J. F. Landau theory of domain wall magnetoelectricity. Phys. Rev. B 81, 224118 (2010).

    ADS  Article  Google Scholar 

  29. 29.

    Lee, S., Chen, R. & Balents, L. Metal-insulator transition in a two-band model for the perovskite nickelates. Phys. Rev. B 84, 165119 (2011).

    ADS  Article  Google Scholar 

  30. 30.

    Zachar, O., Kivelson, S. A. & Emery, V. J. Landau theory of stripe phases in cuprates and nickelates. Phys. Rev. B 57, 1422–1426 (1998).

    ADS  Article  Google Scholar 

  31. 31.

    Papanicolaou, N. Antiferromagnetic domain walls. Phys. Rev. B 51, 15062–15073 (1995).

    ADS  Article  Google Scholar 

  32. 32.

    Scagnoli, V. et al. Role of magnetic and orbital ordering at the metal-insulator transition in NdNiO3. Phys. Rev. B 73, 100409(R) (2006).

    ADS  Article  Google Scholar 

  33. 33.

    Scagnoli, V. et al. Induced noncollinear magnetic order of Nd3+ in NdNiO3 observed by resonant soft x-ray diffraction. Phys. Rev. B 77, 115138 (2008).

    ADS  Article  Google Scholar 

  34. 34.

    McLeod, A. S. et al. Model for quantitative tip-enhanced spectroscopy and the extraction of nanoscale-resolved optical constants. Phys. Rev. B 90, 085136 (2014).

    ADS  Article  Google Scholar 

  35. 35.

    Caviglia, A. D. et al. Electric field control of the LaAlO3/SrTiO3 interface ground state. Nature 456, 624–627 (2008).

    ADS  Article  Google Scholar 

  36. 36.

    Ohtomo, A. & Hwang, H. Y. A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface. Nature 427, 423–426 (2004).

    ADS  Article  Google Scholar 

  37. 37.

    Reyren, N. et al. Superconducting interfaces between insulating oxides. Science 317, 1196–1199 (2007).

    ADS  Article  Google Scholar 

  38. 38.

    Valencia, S. et al. Interface-induced room-temperature multiferroicity in BaTiO3. Nat. Mater. 10, 753–758 (2011).

    ADS  Article  Google Scholar 

  39. 39.

    Ma, E. Y. et al. Mobile metallic domain walls in an all-in-all-out magnetic insulator. Science 350, 538–541 (2015).

    ADS  Article  Google Scholar 

  40. 40.

    Frenken, J. W. & Van der Veen, J. F. Observation of surface melting. Phys. Rev. Lett. 54, 134–136 (1985).

    ADS  Article  Google Scholar 

  41. 41.

    Lipowsky, R. Critical surface phenomena at first-order bulk transitions. Phys. Rev. Lett. 49, 1575–1578 (1982).

    ADS  Article  Google Scholar 

  42. 42.

    Dagotto, E. in Nanoscale Phase Separation and Colossal Magnetoresistance: The Physics of Manganites and Related Compounds Ch. 17 (Springer, Berlin Heidelberg, 2013).

  43. 43.

    Nolting, F. et al. Direct observation of the alignment of ferromagnetic spins by antiferromagnetic spins. Nature 405, 767–769 (2000).

    ADS  Article  Google Scholar 

  44. 44.

    Doran, A. et al. Cryogenic PEEM at the Advanced Light Source. J. Electron Spectrosc. Relat. Phenom. 185, 340–346 (2012).

    Article  Google Scholar 

  45. 45.

    Scholl, A. et al. Observation of antiferromagnetic domains in epitaxial thin films. Science 287, 1014–1016 (2000).

    ADS  Article  Google Scholar 

  46. 46.

    Wu, M. et al. Orbital reflectometry of PrNiO3/PrAlO3 superlattices. Phys. Rev. B 91, 195130 (2015).

    ADS  Article  Google Scholar 

  47. 47.

    Fei, Z. et al. Electronic and plasmonic phenomena at graphene grain boundaries. Nat. Nanotech. 8, 821–825 (2013).

    ADS  Article  Google Scholar 

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This research was supported by ARO grant W911NF-17-1-0543. Development of cryogenic nano-optical instrumentation is supported by DE-SC0018218 and DE-SC-0012375. D.N.B. is in receipt of the Gordon and Betty Moore Foundation’s EPiQS Initiative investigator Grant GBMF4533. E.W.C. and Y.W. acknowledge support from NSF DMR-1508236 and Dept. of Education grant no. P116F140459. Financial support from the Deutsche Forschungsgemeinschaft (DFG) under Grant No. SFB/TRR80 G1 is acknowledged by M.H., M.B., G.C., G.L., P.R., M.M., E.B. and B.K.

Author information




K.W.P., A.S.M and D.N.B. conceived of and conducted the nano-IR experiments, analysed the data, and composed the article. A.C., G.X.N. and A.P. assisted with nano-IR measurements. M.H., M.B., G.C., G.L., P.R., M.M., A.V.B., E.B. and B.K. grew the NdNiO3 film and conducted the XRD and transport measurements. Y.F.W., K.A.D. and E.W.C. performed theoretical studies to interpret domain morphology data in the context of Ising models and Landau theory.

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Correspondence to K. W. Post.

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Supplementary Information, Supplementary Figures S1–S16, Supplementary References 1–36

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Post, K.W., McLeod, A.S., Hepting, M. et al. Coexisting first- and second-order electronic phase transitions in a correlated oxide. Nature Phys 14, 1056–1061 (2018).

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