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ABSTRACT The Ge2Sb2Te5 is a phase-change material widely used in optical memory devices and is a leading candidate for next generation non-volatile random access memory devices which are key

elements of various electronics and portable systems. Despite the compound is under intense investigation its electronic structure is currently not fully understood. The present work sheds

new light on the electronic structure of the Ge2Sb2Te5 crystalline phases. We demonstrate by predicting from first-principles calculations that stable crystal structures of Ge2Sb2Te5 possess

different topological quantum phases: a topological insulator phase is realized in low-temperature structure and Weyl semimetal phase is a characteristic of the high-temperature structure.

Since the structural phase transitions are caused by the temperature the switching between different topologically non-trivial phases can be driven by variation of the temperature. The

obtained results reveal the rich physics of the Ge2Sb2Te5 compound and open previously unexplored possibility for spintronics applications of this material, substantially expanding its

application potential. SIMILAR CONTENT BEING VIEWED BY OTHERS SKYRMIONIC SPIN STRUCTURES IN LAYERED FE5GETE2 UP TO ROOM TEMPERATURE Article Open access 18 October 2022 EXTREMELY LARGE

MAGNETORESISTANCE IN HIGH QUALITY MAGNETIC FE2GE3 SINGLE CRYSTALS Article Open access 25 March 2025 HISTORY-DEPENDENT DOMAIN AND SKYRMION FORMATION IN 2D VAN DER WAALS MAGNET FE3GETE2

Article Open access 31 May 2022 INTRODUCTION The Ge2Sb2Te5 compound is a phase-change material (PCM) which has been long used in optical memory devices such as re-writable DVD-RAM and is

also a leading candidate for next generation non-volatile electronic memory known as phase-change random-access memory (PC-RAM)1,2. Recently, a new concept of nanostructured PCMs has been

developed based on [GeTe]_n_[Sb2Te3]_m_ short-period superlattices, referred to as interfacial phase-change materials3,4,5 among which Ge2Sb2Te5 (_n_ = 2, _m_ = 1) is regarded as a prototype

conventional PCM. Initially it was assumed that in this type of materials the switching between memory states is due to the amorphous-crystalline phase-transition of the separate relatively

thick superlattice sublayers4,5,6. However, latter it was demonstrated that the superlattice kept functioning while the GeTe sublayer thickness was narrowed down to 2–3 GeTe bilayers and

thus it was concluded that the temperature-induced phase-change occurred within the crystalline state, rather than between amorphous and crystalline phases, as was verified with transmission

electron microscopy3. At present, it is established that Ge2Sb2Te5, i.e. [GeTe]_n_=2[Sb2Te3]_m_=1 system can adopt four different hexagonal layered structures in which the primary bonds in

different layers are aligned according to the ordering of Ge, Sb and Te layers7. They are Kooi structure, experimentally the most stable phase of Ge2Sb2Te58, which is formed by nonuple layer

(NL) building blocks, where GeTe bilayers are incorporated into the Sb2Te3 quintuple layer (QL); Petrov structure9, in which the [GeTe]2 blocks are sandwiched between Sb2Te3 QLs with

Ge-Te-Te-Ge sequence within the block; Inverted-Petrov structure with Te-Ge-Ge-Te sequence; and so-called Ferro structure, in which the atomic layer sequence in the [GeTe]2 block has

Ge-Te-Ge-Te order, i.e. like in ferroelectric bulk GeTe. The relative stability of these four structures depends on temperature. Earlier it was shown by means of _ab-initio_ calculations of

enthalpy as a function of temperature10 the Kooi phase has the lowest enthalpy at 0 K, in agreement with earlier density functional theory (DFT) calculation7 and experiment8. However, upon

raising the temperature the enthalpy of the Kooi structure increases and above ≈125 K the Ferro phase becomes the most stable one10. The metastable Petrov and Inverted Petrov phases are

involved into atomic mechanism of the phase transition between stable Kooi and Ferro phases10. Despite the results of ref. 10 correctly reproduce the sequence and stability of the Ge2Sb2Te5

crystal structures they underestimate the transition temperature which according to experiments is higher than the room temperature. Despite the advances in comprehension of the crystal

structure and atomic mechanisms of crystal phase transformations the electronic structure of Ge2Sb2Te5 phases is currently not fully understood. For the stable low-temperature NL structured

Kooi phase the narrow-gap band insulator (BI) phase has been obtained theoretically7,11,12,13. It is in contrast to related NL-structured Ge2Bi2Te5 and Sn2Sb(Bi)2Te5 compounds, which are

shown to be topological insulators (TIs)12,14. The [GeTe]_n_[Sb2Te3]_m_ compound with opposite _n, m_ indices (_n_ = 1, _m_ = 2) has also been predicted to be TI15. The calculations for

Ferro and Petrov structures also predicted the BI phase, while another metastable structure, the Inverted Petrov structure is shown to possess the Dirac semimetal quantum phase7. In this

work, we focus on electronic structure of stable low-temperature Kooi and high-temperature Ferro structures. We start with ordered Kooi structure which was also considered in the previous

works7,12. The equilibrium crystal structure of the Kooi phase, obtained using VASP code (see details in the Method section) is shown in Fig. 1(a). The calculated bulk band structure

demonstrates the insulating state with a gap of 25.2 meV in the middle of the Γ-A direction (Fig. 1(b), red lines) which is trivial band insulator in terms of the topological invariant that

is in agreement with earlier results7,11,12. The obtained small band-gap value may be an indication that the system is close to the topological quantum phase transition (TQPT) and can be

converted into the topological phase by increasing spin-orbit interaction strength. We artificially increased the spin-orbit interaction strength _λ_ in the ordered equilibrium structure and

found that it leads to shift of the gap towards the A point along with its narrowing. Upon further increasing the spin-orbit interaction strength the system has gone through the critical

point of the TQPT (at _λ/λ_0 ≈ 1.2), the gap becomes inverted achieving at _λ/λ_0 = 1.4 a width of 76 meV at the A point (Fig. 1(c)). This result is in line with the fact that the TI phase

was predicted for Ge2Bi2Te512 in which the atomic spin-orbit coupling strength is larger owing to the larger atomic mass of Bi as compared to Sb. The bulk band inverted topology should

manifest itself in formation of the spin-polarized Dirac state at the surface. As can be seen in Fig. 1(d) the gapless surface state with typical for related NL-structured Ge2Bi2Te5 and

Sn2Sb(Bi)2Te5 TIs dog-leg dispersion12,14 arises. However, it is known from experiments that stable Ge2Sb2Te5 contains mixed Ge/Sb atomic layers16. Earlier, the influence of Ge/Sb mixing on

electronic structure of the Ge2Sb2Te5 Kooi phase was considered within ordered 2 × 2 supercell approach11. It was demonstrated that invariant depends on relative concentration of Ge in the

inner and outer Ge/Sb layers of NL (which was varied from 0 to 100% in steps of 25% in that model, containing 4 atoms in an atomic plane). It was shown that the material is trivial BI when

the Ge atoms completely occupy inner layers (as in Fig. 1(a)) while it is TI at 50/50 mixing in the Ge/Sb layers. We took into account the Ge/Sb mixing in the calculations within virtual

crystal approximation (VCA) using ABINIT code. First we checked the band structure for the ordered phase with ABINIT code and found it in a good agreement with the VASP result (Fig. 1(b),

dashed blue lines). The calculated spectrum has a gap of 29.5 meV in the middle of the Γ-A direction. Next, according to the experiment16, we constructed Ge0.56/Sb0.44 and Ge0.44/Sb0.56

virtual atoms for the outer and inner Ge/Sb layers of NL, respectively. We find that at normal, zero-pressure conditions the minimum gap of 61 meV appears at the A point (Fig. 1(e)) and,

being inverted (Fig. 1(f)) results in non-trivial topological invariant . This signifies that the Kooi structure possesses the TI quantum phase. Thereby we can conclude that Ge/Sb mixing in

the Ge2Sb2Te5 Kooi structure effectively increases the spin-orbit interaction. As can be seen in Fig. 1(g) presenting the surface band structure, calculated for 5 NL slab of the Kooi phase

with Ge/Sb mixing, the topological surface state with the Dirac point at the Fermi level arises in the spectrum. The distinctive feature of the Ferro structure as opposed to other Ge2Sb2Te5

phases is the lack of inversion symmetry owing to Ge-Te-Ge-Te layer sequence in the [GeTe]2 block (Fig. 2 (a)). It results in the spin-orbit splitting of the bulk energy spectrum (Fig. 2(b))

which resembles the Rashba-like band splitting in the bulk GeTe17. The presented spectrum has a tiny gap of 11 meV in the A–H direction at _k__x_ ≈ 0.1 Å−1 away from the A point. Near the

gap the spin texture differs from Rashba spin-helical picture and demonstrates almost collinear spin alignment perpendicular to the A–H (_k__x_) direction with sizable _S__z_ component of

the same sign both below and above the gap (Fig. 2(c)). Away from the H–A–L plane at _k__z_ = _π/c_ ± 0.015 Å−1 (where _k__z_ = _π/c_ is the H–A–L plane) the gap closes forming a pair of the

Weyl nodes (Fig. 2(d)) that is distinctive feature of the topological Weyl semimetal (TWS) phase. In principle, TWS can be realized by breaking either time-reversal or inversion symmetry of

topological Dirac semimetals18. In this regard, the existence of the TWS in the Ferro phase can be understood from the comparison with the intermediate Inverted Petrov structure. The

Inverted Petrov structure possessing the Dirac semimetal phase differs from the Ferro structure only in the atomic layer sequence within [GeTe]2 block so that the latter one is inversion

asymmetric. The Weyl fermions in the bulk are predicted to provide realization of the chiral anomaly, giving rise to a negative magnetoresistance under parallel electric and magnetic fields,

the semi-quantized anomalous Hall effect, unusual optical conductivity, non-local transport and local non-conservation of the current19,20,21,22,23,24,25. At the surface the bulk band

topology should manifest itself via formation of unusual surface states which form disjoint Fermi arcs which connect the projections of the pairs of Weyl nodes onto the surface Brillouin

zone26,27. The Fermi arc surface states are predicted to show unconventional quantum oscillations in magneto-transport, as well as unusual quantum interference effects in tunneling

spectroscopy27,28,29,30. The Ferro phase can adopt six different surface terminations depending on Sb2Te3 QL and GeTe bilayers sequence near the cleavage plane. These terminations should

differ in bending of the surface potential owing to polarity in the GeTe bilayers (Ge+0.4, Te−0.4). The geometries of the terminations are shown schematically in insets in Fig. 3. The

calculated surface electronic spectra (Fig. 3, odd columns) demonstrate that all surface terminations hold the trivial Rashba-split surface states resulting from splitting off from bulk

bands due to the band-bending effect which is negative for QL-GeTe-GeTe-, GeTe-GeTe-QL-, and GeTe-QL-GeTe- terminations (first column in Fig. 3) and positive for terminations shown in the

third column. Besides these states, as can be seen in the Fermi surface maps (Fig. 3, even columns), each surface termination holds the Fermi arcs connecting the Weyl’s pairs. In most cases

they connect the Weyl nodes within each - pair while in case of TeGe-QL-TeGe- termination the arcs connect points of neighboring pairs via the hole-like Rashba surface state which crosses

the Fermi level twice in the - direction, however does it once in - and touches the Weyl nodes on the conduction band side. Similar effect of the Weyl nodes reconnecting has been observed

recently in the TWS phase arising in BiTeI under pressure31. In summary, on the basis of _ab-initio_ calculations we provide an important ingredient to the physics of prospective

phase-change material Ge2Sb2Te5 demonstrating that temperature-induced structural phase transformation is accompanied by the quantum topological phase transition from TI phase in the

low-temperature Kooi crystal structure to TWS phase in the high-temperature Ferro structure. We also demonstrate that the Ge/Sb mixing in the low-temperature structure is crucial for

formation of the TI phase. Together with earlier predicted Dirac semimetal phase for intermediate metastable Inverted Petrov structure the TI and Weyl semimetal phases form a rich

topological family realized in the same material and switching between the topological phases is ensured by the temperature. The Dirac surface states of TI, prospective for spintronic

applications as well as exotic bulk and surface electronic states of TWS providing an ideal platform for many novel physical phenomena, such as negative magnetoresistance, anomalous quantum

Hall effect and chiral magnetic effect can be realized in Ge2Sb2Te5, substantially expanding the application potential of this material. Since Ge2Sb2Te5 compound naturally has a polycrystal

structure with randomly oriented crystallites the utilization of the predicted surface states of the topological quantum phases requires precise epitaxial growth of the Ge2Sb2Te5 films.

METHODS Electronic structure calculations were carried out within density functional theory (DFT). For bulk band structure calculations we used the Vienna Ab Initio Simulation Package

(VASP)32,33. The interaction between the ion cores and valence electrons was described by the projector augmented-wave (PAW) method34,35. Relativistic effects, including spin-orbit

interaction (SOI), were taken into account. For this calculations, the PBE exchange-correlation functional36 was used and DFT-D3 van der Walls correction37 was applied for accurate structure

optimization. To treat the disordered Kooi phase we employed a virtual crystal approximation (VCA) as implemented in the ABINIT code38, where the averaged potential of a virtual atom

occupying a site in the Ge/Sb sublattice is defined as a mixture _V_V_CA_ = _xV_G_e_ + (1 − _x)V_S_b_ of Ge (_V_G_e_) and Sb (_V_S_b_) pseudopotentials. In ABINIT calculations we used

GGA-PBE Hartwigsen-Goedecker-Hutter (HGH) relativistic norm-conserving pseudopotentials which include the SOI39. For surface electronic structure calculations for the Weyl phase, first the

results of VASP calculations were used in the WANNIER90 code40 to construct tight-binding model. The chosen basis consists of six spinor _p_-type orbitals for each atom: , , , , , . The

low-lying _s_ orbitals are not taken into consideration. Surface tight-binding model is derived from the bulk one with inclusion of band-bending effects obtained from direct surface

calculations within DFT. The surface spectrum has been calculated within surface Green function approach41,42. The invariant is calculated from the parity of occupied electronic states at

the time-reversal invariant points of the bulk Brillouin zone43. ADDITIONAL INFORMATION HOW TO CITE THIS ARTICLE: Eremeev, S. V. _et al_. Temperature-driven topological quantum phase

transitions in a phase-change material Ge2Sb2Te5. _Sci. Rep._ 6, 38799; doi: 10.1038/srep38799 (2016). PUBLISHER'S NOTE: Springer Nature remains neutral with regard to jurisdictional

claims in published maps and institutional affiliations. REFERENCES * Burr, G. W. et al. Phase change memory technology. J. Vac. Sci. Technol. B 28, 223–262 (2010). Article  CAS  Google

Scholar  * Lencer, D., Salinga, M. & Wuttig, M. Design Rules for Phase-Change Materials in Data Storage Applications. Adv. Mater. 23, 2030–2058 (2011). Article  CAS  Google Scholar  *

Simpson, R. E. et al. Interfacial phase-change memory. Nature Nanotechnol. 6, 501–505 (2011). Article  ADS  CAS  Google Scholar  * Chong, T. C. et al. Phase change random access memory cell

with superlattice-like structure. Appl. Phys. Lett. 88, 122114 (2006). Article  ADS  Google Scholar  * Tominaga, J. et al. Giant multiferroic effects in topological GeTe-Sb2Te3

superlattices. Sci. Technol. Adv. Mater. 16, 014402 (2015). Article  Google Scholar  * Chong, T. C. et al. Crystalline amorphous semiconductor superlattice. Phys. Rev. Lett. 100, 136101

(2008). Article  ADS  CAS  Google Scholar  * Tominaga, J., Kolobov, A. V., Fons, P., Nakano, T. & Murakami, S. Ferroelectric Order Control of the Dirac-Semimetal Phase in GeTe-Sb2Te3

Superlattices. Adv. Mater. Interfaces 1, 1300027 (2014). Article  Google Scholar  * Kooi, B. J. & De Hosson, J. Th. M. Electron diffraction and high-resolution transmission electron

microscopy of the high temperature crystal structures of Ge_x_Sb2Te3+_x_ (_x_ = 1,2,3) phase change material. J. Appl. Phys. 92, 3584–3590 (2002). Article  ADS  CAS  Google Scholar  *

Petrov, I. I., Imamov, R. M. & Pinsker, Z. G. Electron-diffraction determination of the structures of Ge2Sb2Te5 and GeSb4Te7 . Sov. Phys. Crystallogr. 13, 339–342 (1968). Google Scholar

  * Yu, X. & Robertson, J. Modeling of switching mechanism in GeSbTe chalcogenide superlattices. Sci. Rep. 5, 12612 (2015). Article  ADS  CAS  Google Scholar  * Silkin, I. V., Koroteev,

Yu. M., Bihlmayer, G. & Chulkov, E. V. Influence of the Ge–Sb sublattice atomic composition on the topological electronic properties of Ge2Sb2Te5 . Applied Surface Science 267, 169–172

(2013). Article  ADS  CAS  Google Scholar  * Kim, J., Kim, J., Kim, K.-S. & Jhi, S.-H. Topological Phase Transition in the Interaction of Surface Dirac Fermions in Heterostructures.

Phys. Rev. Lett. 109, 146601 (2012). Article  ADS  Google Scholar  * Kim, J., Kim, J. & Jhi, S.-H. Prediction of topological insulating behavior in crystalline Ge-Sb-Te. Phys. Rev. B 82,

201312(R) (2010). Article  ADS  Google Scholar  * Eremeev, S. V. et al. Sublattice effect on topological surface states in complex (SnTe)_n_>1(Bi2Te3)_m_=1 compounds. Phys. Rev. B

91, 245145 (2015). Article  ADS  Google Scholar  * Eremeev, S. V. et al. Atom-specific spin mapping and buried topological states in a homologous series of topological insulators. Nature

Commun. 3, 635 (2012). Article  ADS  Google Scholar  * Matsunaga, T., Yamada, N. & Kubota, Y. Structures of stable and metastable Ge2Sb2Te5, an intermetallic compound in GeTe–Sb2Te3

pseudobinary systems. Acta Crystallogr. B 60, 685–691 (2004). Article  Google Scholar  * Di Sante, D., Barone, P., Bertacco, R. & Picozzi, S. Electric control of the giant Rashba effect

in bulk GeTe. Adv. Mater. 25, 509–513 (2013). Article  CAS  Google Scholar  * Burkov, A. A. & Balents, L. Weyl semimetal in a topological insulator multilayer. Phys. Rev. Lett. 107,

127205 (2011). Article  ADS  CAS  Google Scholar  * Zyuzin, A. A. & Burkov, A. A. Topological response in Weyl semimetals and the chiral anomaly. Phys. Rev. B 86, 115133 (2012). Article

  ADS  Google Scholar  * Yang, K.-Y., Lu, Y.-M. & Ran, Y. Quantum Hall effects in a Weyl semimetal: Possible application in pyrochlore iridates. Phys. Rev. B 84, 075129 (2011). Article 

ADS  Google Scholar  * Son, D. T. & Spivak, B. Z. Chiral anomaly and classical negative magnetoresistance of Weyl metals. Phys. Rev. B 88, 104412 (2013). Article  ADS  Google Scholar  *

Liu, C.-X., Ye, P. & Qi, X.-L. Chiral gauge field and axial anomaly in a Weyl semimetal. Phys. Rev. B 87, 235306 (2013). Article  ADS  Google Scholar  * Wei, H., Chao, S.-P. & Aji,

V. Excitonic phases from Weyl semimetals. Phys. Rev. Lett. 109, 196403 (2012). Article  ADS  Google Scholar  * Ashby, P. E. C. & Carbotte, J. P. Magneto-optical conductivity of Weyl

semimetals. Phys. Rev. B 87, 245131 (2013). Article  ADS  Google Scholar  * Landsteiner, K. Anomalous transport of Weyl fermions in Weyl semimetals. Phys. Rev. B 89, 075124 (2014). Article 

ADS  Google Scholar  * Wan, X., Turner, A. M., Vishwanath, A. & Savrasov, S. Y. Topological semimetal and Fermi-arc surface states in the electronic structure of pyrochlore iridates.

Phys. Rev. B 83, 205101 (2011). Article  ADS  Google Scholar  * Hosur, P. Friedel oscillations due to Fermi arcs in Weyl semimetals. Phys. Rev. B 86, 195102 (2012). Article  ADS  Google

Scholar  * Ojanen, T. Helical Fermi arcs and surface states in time-reversal invariant Weyl semimetals. Phys. Rev. B 87, 245112 (2013). Article  ADS  Google Scholar  * Potter, A. C., Kimchi,

I. & Vishwanath, A. Quantum oscillations from surface Fermi arcs in Weyl and Dirac semimetals. Nature Commun. 5, 5161 (2014). Article  ADS  CAS  Google Scholar  * Zhang, Y., Bulmash,

D., Hosur, P., Potter, A. C. & Vishwanath, A. Quantum oscillations from generic surface Fermi arcs and bulk chiral modes in Weyl semimetals. Sci. Rep. 6, 23741 (2016). Article  ADS  CAS

  Google Scholar  * Rusinov, I. P. et al. Pressure effects on crystal and electronic structure of bismuth tellurohalides. New J. Phys. 18, 113003 (2016). Article  ADS  Google Scholar  *

Kresse, G. & Hafner, J. _Ab initio_ molecular dynamics for open-shell transition metals. Phys. Rev. B 48, 13115 (1993). Article  ADS  CAS  Google Scholar  * Kresse, G. & Furthmüller,

J. Efficient iterative schemes for _ab initio_ total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169 (1996). Article  ADS  CAS  Google Scholar  * Blöchl, P. E.

Projector augmented-wave method. Phys. Rev. B 50, 17953 (1994). Article  ADS  Google Scholar  * Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave

method. Phys. Rev. B 59, 1758 (1999). Article  ADS  CAS  Google Scholar  * Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77,

3865 (1996). Article  ADS  CAS  Google Scholar  * Grimme, S., Antony, J., Ehrlich, S. & Krieg, H. A consistent and accurate _ab initio_ parametrization of density functional dispersion

correction (DFT-D) for the 94 elements H-Pu. J. Chem. Phys. 132, 154104 (2010). Article  ADS  Google Scholar  * Gonze, X. et al. ABINIT: First-principles approach to material and nanosystem

properties. Comput. Phys. Commun. 180, 2582 (2009). Article  ADS  CAS  Google Scholar  * Krack, M. Pseudopotentials for H to Kr optimized for gradient-corrected exchange-correlation

functionals. Theor. Chem. Acc. 114, 145 (2005). Article  CAS  Google Scholar  * Marzari, N. & Vanderbilt, D. Maximally localized generalized Wannier functions for composite energy bands.

Phys. Rev. B 56, 12847 (1997). Article  ADS  CAS  Google Scholar  * Lopez Sancho, M. P., Lopez Sancho, J. M., Sancho, J. M. L. & Rubio, J. Highly convergent schemes for the calculation

of bulk and surface Green functions. J. Phys. F 15, 851 (1985). Article  ADS  Google Scholar  * Henk, J. & Schattke, W. A subroutine package for computing Green’s functions of relaxed

surfaces by the renormalization method. Comput. Phys. Commun. 77, 69–83 (1993). Article  ADS  CAS  Google Scholar  * Fu, L. & Kane, C. L. Topological insulators with inversion symmetry.

Phys. Rev. B 76, 045302 (2007). Article  ADS  Google Scholar  Download references ACKNOWLEDGEMENTS We acknowledge partial support from the Basque Country Government, Departamento de

Educación, Universidades e Investigación (Grant No. IT-756-13), the Spanish Ministerio de Ciencia e Innovación (Grants No. FIS2013-48286-C02-01-P and FIS2013-48286-C02-02-P), the Tomsk State

University Academic D.I. Mendeleev Fund Program (Grant No. 8.1.05.2015), and Saint Petersburg State University (Grant No. 15.61.202.2015). Calculations were partly performed using

computational resources provided by Resource Center “Computer Center of SPbU” (http://cc.spbu.ru) and the SKIF-Cyberia supercomputer at the National Research Tomsk State University. AUTHOR

INFORMATION AUTHORS AND AFFILIATIONS * Institute of Strength Physics and Materials Science, Tomsk, 634055, Russia S. V. Eremeev * Tomsk State University, Tomsk, 634050, Russia S. V. Eremeev,

 I. P. Rusinov & E. V. Chulkov * Saint Petersburg State University, Saint Petersburg, 198504, Russia S. V. Eremeev, I. P. Rusinov & E. V. Chulkov * Donostia International Physics

Center (DIPC), 20018 San Sebastián/Donostia, Basque Country, Spain S. V. Eremeev, P. M. Echenique & E. V. Chulkov * Departamento de Física de Materiales UPV/EHU, Centro de Física de

Materiales CFM - MPC and Centro Mixto CSIC-UPV/EHU, San Sebastián/Donostia, 20080, Basque Country, Spain P. M. Echenique & E. V. Chulkov Authors * S. V. Eremeev View author publications

You can also search for this author inPubMed Google Scholar * I. P. Rusinov View author publications You can also search for this author inPubMed Google Scholar * P. M. Echenique View author

publications You can also search for this author inPubMed Google Scholar * E. V. Chulkov View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS

The calculations were performed by S.V.E. and I.P.R. S.V.E., I.P.R., P.M.E. and E.V.C. analyzed the data, and contributed to the discussion and writing the manuscript. ETHICS DECLARATIONS

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