Metallization of vanadium dioxide driven by large phonon entropy

Phase competition underlies many remarkable and technologically important phenomena in transition metal oxides. Vanadium dioxide (VO2) exhibits a first-order metal–insulator transition (MIT) near room temperature, where conductivity is suppressed and the lattice changes from tetragonal to monoclinic on cooling. Ongoing attempts to explain this coupled structural and electronic transition begin with two alternative starting points: a Peierls MIT driven by instabilities in electron–lattice dynamics and a Mott MIT where strong electron–electron correlations drive charge localization. A key missing piece of the VO2 puzzle is the role of lattice vibrations. Moreover, a comprehensive thermodynamic treatment must integrate both entropic and energetic aspects of the transition. Here we report that the entropy driving the MIT in VO2 is dominated by strongly anharmonic phonons rather than electronic contributions, and provide a direct determination of phonon dispersions. Our ab initio calculations identify softer bonding in the tetragonal phase, relative to the monoclinic phase, as the origin of the large vibrational entropy stabilizing the metallic rutile phase. They further reveal how a balance between higher entropy in the metal and orbital-driven lower energy in the insulator fully describes the thermodynamic forces controlling the MIT. Our study illustrates the critical role of anharmonic lattice dynamics in metal oxide phase competition, and provides guidance for the predictive design of new materials.

[1]  John B. Goodenough,et al.  The two components of the crystallographic transition in VO2 , 1971 .

[2]  Peihong Zhang,et al.  VO2: Orbital competition, magnetism, and phase stability , 2012 .

[3]  Nevill Francis Mott,et al.  Metal-insulator transition in vanadium dioxide , 1975 .

[4]  Jiao Y. Y. Lin,et al.  Design and operation of the wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source. , 2012, The Review of scientific instruments.

[5]  J. P. Remeika,et al.  X-ray diffraction study of metallic VO$sub 2$ , 1974 .

[6]  Silke Biermann,et al.  Effective band-structure in the insulating phase versus strong dynamical correlations in metallic VO2 , 2007, 0704.0902.

[7]  J. Zaanen,et al.  Density-functional theory and strong interactions: Orbital ordering in Mott-Hubbard insulators. , 1995, Physical review. B, Condensed matter.

[8]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[9]  A. Guinier,et al.  Désordre linéaire dans les cristaux (cas du silicium, du quartz, et des pérovskites ferroélectriques) , 1970 .

[10]  Isao Tanaka,et al.  First-principles calculations of the ferroelastic transition between rutile-type and CaCl2-type SiO2 at high pressures , 2008 .

[11]  S. Parkin,et al.  Suppression of Metal-Insulator Transition in VO2 by Electric Field–Induced Oxygen Vacancy Formation , 2013, Science.

[12]  David H. Cobden,et al.  Measurement of a solid-state triple point at the metal–insulator transition in VO2 , 2013, Nature.

[13]  Pouget,et al.  Comment on "VO2: Peierls or Mott-Hubbard? A view from band theory" , 1994, Physical Review Letters.

[14]  V. Eyert,et al.  VO2: a novel view from band theory. , 2011, Physical review letters.

[15]  K. Sugiyama,et al.  The crystal structure of rutile as a function of temperature up to 1600°C , 1991 .

[16]  Kress,et al.  Lattice dynamics of oxides with rutile structure and instabilities at the metal-semiconductor phase transitions of NbO2 and VO2. , 1985, Physical review. B, Condensed matter.

[17]  C. J. Hearn.  Phonon softening and the metal-insulator transition in VO2 , 1972 .

[18]  Stuart S. P. Parkin,et al.  Control of the metal–insulator transition in vanadium dioxide by modifying orbital occupancy , 2013, Nature Physics.

[19]  C. N. Berglund,et al.  Electronic Properties of V O 2 near the Semiconductor-Metal Transition , 1969 .

[20]  Chang-Jong Kang,et al.  Correlation-assisted phonon softening and the orbital-selective Peierls transition in VO 2 , 2012, 1207.1770.

[21]  R. Srivastava,et al.  Raman Spectrum of Semiconducting and Metallic V O 2 , 1971 .

[22]  G. Scuseria,et al.  Hybrid functionals based on a screened Coulomb potential , 2003 .

[23]  B. Pan,et al.  The dynamical process of the phase transition from VO2(M) to VO2(R) , 2011 .

[24]  Nicholas D M Hine,et al.  Vanadium dioxide: a Peierls-Mott insulator stable against disorder. , 2012, Physical review letters.

[25]  U. Ragnarsson,et al.  A Refinement of the Structure of VO2. , 1970 .

[26]  J. Traylor.  The Lattice Dynamics of Rutile. , 1971 .

[27]  V. Müller,et al.  Elastic behavior near the metal-insulator transition of VO 2 , 1999 .

[28]  J. Cohen,et al.  Diffuse x-ray scattering due to the lattice instability near the metal-semiconductor transition in VO/sub 2/ , 1978 .

[29]  G. Ice,et al.  Design and performance of the 33-BM beamline at the Advanced Photon Source , 2011 .

[30]  G. Kresse,et al.  From ultrasoft pseudopotentials to the projector augmented-wave method , 1999 .

[31]  Blöchl,et al.  Projector augmented-wave method. , 1994, Physical review. B, Condensed matter.

[32]  A Tanaka,et al.  Orbital-assisted metal-insulator transition in VO2. , 2005, Physical review letters.

[33]  Volker Eyert,et al.  The metal‐insulator transitions of VO2: A band theoretical approach , 2002, Annalen der Physik.

[34]  S. W. Lovesey,et al.  Theory of neutron scattering from condensed matter , 1984 .

[35]  Kresse,et al.  Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. , 1996, Physical review. B, Condensed matter.

[36]  M. Kawasaki,et al.  Collective bulk carrier delocalization driven by electrostatic surface charge accumulation , 2012, Nature.

[37]  G. Kresse,et al.  Ab initio molecular dynamics for liquid metals. , 1993 .

[38]  Sarbajit Banerjee,et al.  Microscopic and Nanoscale Perspective of the Metal−Insulator Phase Transitions of VO2: Some New Twists to an Old Tale , 2011 .

[39]  Igor A. Abrikosov,et al.  Temperature dependent effective potential method for accurate free energy calculations of solids , 2013, 1303.1145.

[40]  G. Bihlmayer,et al.  Coulomb correlations and orbital polarization in the metal-insulator transition of VO2 , 2003, cond-mat/0310216.

[41]  D. Khomskii,et al.  Orbitally induced Peierls state in spinels. , 2004, Physical review letters.

[42]  B. Fultz,et al.  Vibrational and electronic entropy of β-cerium and γ-cerium measured by inelastic neutron scattering , 2002 .

[43]  A. Navrotsky,et al.  Experimental study of the electronic and lattice contributions to the VO2 transition , 1978 .

[44]  Allen,et al.  VO2: Peierls or Mott-Hubbard? A view from band theory. , 1994, Physical review letters.

[45]  P. M. Raccah,et al.  Structural fluctuations in NbO/sub 2/ at high temperatures , 1978 .