Evidence for a charge-density-wave instability in the purple bronze K0·9Mo6O17

Escribe-Filippini, C.; Konate, K.; Marcus, J.; Schlenker, C.; Almairac, R.; Ayroles, R.; Roucau, C.

doi:10.1080/13642818408238857

Cited by 53 publications

(27 citation statements)

References 18 publications

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confidence: 66%

“…The quasi-1D character of the FS is likely critical to the unusual properties of this materials as it naturally provides an exceptional nesting condition [44,45]. Indeed, the measured CDW vectors agree well with FS nesting vectors that connect two crossing points of the quasi-1D FS sheets [46,47].In this letter, we show that there is a enhancement of CDW transition temperature and even larger enhancement of the CDW energy gap (by an order of magnitude) on the surface of K 0.9 Mo 6 O 17 . More surprisingly, we demonstrate that this materials lacks usual signatures of strong el-ph coupling.…”

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confidence: 65%

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Discovery of an Unconventional Charge Density Wave at the Surface ofK0.9Mo6O17
Mou
¹
,
Sapkota
²
,
Kung
³

et al. 2016
Phys. Rev. Lett.
29
3
22
0
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We use Angle Resolved Photoemission Spectroscopy (ARPES), Raman spectroscopy, Low Energy Electron Diffraction (LEED) and x-ray scattering to reveal an unusual electronically mediated charge density wave (CDW) in K0.9Mo6O17. Not only does K0.9Mo6O17 lack signatures of electron-phonon coupling, but it also hosts an extraordinary surface CDW, with TS CDW =220 K nearly twice that of the bulk CDW, TB CDW =115 K. While the bulk CDW has a BCS-like gap of 12 meV, the surface gap is ten times larger and well in the strong coupling regime. Strong coupling behavior combined with the absence of signatures of strong electron-phonon coupling indicates that the CDW is likely mediated by electronic interactions enhanced by low dimensionality.PACS numbers: 71.45. Lr, 68.47.Gh Most known CDW materials are mediated by strong electron-phonon (el-ph) interaction [1], as confirmed by observation of large kinks in the dispersion by ARPES [2][3][4][5][6]. Some of the best known examples are the layered transition-metal dichacogenides and tellurides [7][8][9], where charge order often coexists and competes with superconductivity, due to their common el-ph origin [4,5,8,[10][11][12][13][14]. A CDW has been discovered within the pseudogap state of the cuprates [15][16][17][18][19][20][21][22][23][24], although its origin remains unclear. The observation of phonon anomalies suggests el-ph coupling may play a role [25][26][27], however, a number of theoretical models suggest that this CDW could be electronically mediated [28][29][30][31]. Electronelectron (el-el) interactions are also thought to be responsible for the CDW found in related cuprate ladder compounds [32].The properties of materials can be dramatically altered at the surface. In CDWs often the transition temperature is enhanced at the surface [33], an effect known as an extraordinary transition [34,35]. Recently such effect was also reported in a monolayer [36][37][38]. The increased T C has been attributed to enhanced interactions due to the decreased dimensionality [39,40]. In this letter, we show that K 0.9 Mo 6 O 17 has an enhanced surface transition temperature, and a surface energy gap an order of magnitude larger than the bulk. Despite the strong coupling nature of the surface order, K 0.9 Mo 6 O 17 shows no signatures of strong el-ph coupling, either in the phonon or electronic structure, making it a new candidate for an el-el mediated CDW. K 0.9 Mo 6 O 17 belongs to a family of materials including both one dimensional (1D) and two dimensional (2D) systems [41] and has been regarded as a model quasi-2D CDW material with T B CDW ∼ 115 K [42]. Its crystal structure [43] consists of a stacking of molybdenumoxygen slabs (Mo 6 O 17 ) along the hexagonal c axis with potassium atoms intercalated between these slabs. The Mo-O layers consist of Mo 2 O 10 zigzag chains along three directions, and the 2D Fermi surface (FS) can be constructed by superimposing three sets of quasi-1D FS lines, with a weak hybridization. The quasi-1D character of the FS is likely critical to the un...

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supporting

confidence: 66%

supporting

confidence: 65%

Discovery of an Unconventional Charge Density Wave at the Surface ofK0.9Mo6O17
Mou
¹
,
Sapkota
²
,
Kung
³

et al. 2016
Phys. Rev. Lett.
29
3
22
0
View full text Add to dashboard Cite

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“…This is the socalled hidden nesting property. These calculations predict nesting wave vectors (a Ã /2, 0 0) and equivalent, which have been observed by electron diffraction and X-ray diffuse scattering [5]. This has been corroborated by angle-resolved photoemission spectroscopy and Fermi surface imaging [6].…”

Section: Introductionmentioning

confidence: 79%

“…They are in the shape of small platelets perpendicular to the c-axis [5]. Magnetic torque measurements have been performed by the cantilever technique in static fields up to 28 T at temperatures between 380 mK and 4.2 K [17].…”

Section: Methodsmentioning

confidence: 99%

High magnetic field studies of the charge density wave state of the quasi-two-dimensional conductor KMO6O17

Dumas

Guyot

Balaska

et al. 2004

Physica B: Condensed Matter

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“…However, the value of ððDC p Þ=RÞ=p is at least a factor of 2 smaller than in the doped phosphate tungsten bronzes. In the case of the quasi-2D Mo purple bronze KMo 6 O 17 , which shows a commensurate metal -metal transition at 120 K, the experimental value of ððDC p Þ=RÞ=p is comparable to that of the blue bronze and also much smaller that in K x P 4 W 8 O 32 [14]. One may note that the crystal structure is very similar in both classes of materials.…”

Section: Discussionmentioning

confidence: 58%

Specific heat anomalies in the quasi two-dimensional monophosphate tungsten bronzes KxP4W8O32

Бондаренко

Brill

Dumas³

et al. 2004

Solid State Communications

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Evidence for a charge-density-wave instability in the purple bronze K_0·9Mo₆O₁₇

Cited by 53 publications

References 18 publications

Discovery of an Unconventional Charge Density Wave at the Surface ofK0.9Mo6O17
Mou
¹
,
Sapkota
²
,
Kung
³

et al. 2016
Phys. Rev. Lett.
29
3
22
0
View full text Add to dashboard Cite

Discovery of an Unconventional Charge Density Wave at the Surface ofK0.9Mo6O17
Mou
¹
,
Sapkota
²
,
Kung
³

et al. 2016
Phys. Rev. Lett.
29
3
22
0
View full text Add to dashboard Cite

High magnetic field studies of the charge density wave state of the quasi-two-dimensional conductor KMO6O17

Specific heat anomalies in the quasi two-dimensional monophosphate tungsten bronzes KxP4W8O32

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Evidence for a charge-density-wave instability in the purple bronze K0·9Mo6O17

Cited by 53 publications

References 18 publications

Discovery of an Unconventional Charge Density Wave at the Surface ofK0.9Mo6O17Mou1, Sapkota2, Kung3 et al. 2016Phys. Rev. Lett.293220View full textAdd to dashboardCite

Discovery of an Unconventional Charge Density Wave at the Surface ofK0.9Mo6O17Mou1, Sapkota2, Kung3 et al. 2016Phys. Rev. Lett.293220View full textAdd to dashboardCite

High magnetic field studies of the charge density wave state of the quasi-two-dimensional conductor KMO6O17

Specific heat anomalies in the quasi two-dimensional monophosphate tungsten bronzes KxP4W8O32

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Evidence for a charge-density-wave instability in the purple bronze K_0·9Mo₆O₁₇

Discovery of an Unconventional Charge Density Wave at the Surface ofK0.9Mo6O17
Mou
¹
,
Sapkota
²
,
Kung
³

et al. 2016
Phys. Rev. Lett.
29
3
22
0
View full text Add to dashboard Cite

Discovery of an Unconventional Charge Density Wave at the Surface ofK0.9Mo6O17
Mou
¹
,
Sapkota
²
,
Kung
³

et al. 2016
Phys. Rev. Lett.
29
3
22
0
View full text Add to dashboard Cite