| Records |
| Author |
Bourgeois, J.; Hervieu, M.; Poienar, M.; Abakumov, A.M.; Elkaïm, E.; Sougrati, M.T.; Porcher, F.; Damay, F.; Rouquette, J.; Van Tendeloo, G.; Maignan, A.; Haines, J.; Martin, C.; |
| Title |
Evidence of oxygen-dependent modulation in LuFe2O4 |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
6 |
Pages |
064102-064120,10 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
A polycrystalline sample of LuFe2O4 has been investigated by means of powder synchrotron x-ray and neutron diffraction and transmission electron microscopy (TEM), along with Mössbauer spectroscopy and transport and magnetic properties. A monoclinic distortion is unambiguously evidenced, and the crystal structure is refined in the monoclinic C2/m space group [aM = 5.9563(1) Å, bM = 3.4372(1) Å, cM = 8.6431(1) Å, β = 103.24(1)°]. Along with the previously reported modulations distinctive of the charge-ordering (CO) of the iron species, a new type of incommensurate order is observed, characterized by a vector q⃗1 = α1a⃗M* + γ1c⃗M* (with α1 ≅ 0.55, γ1 ≅ 0.13). In situ heating TEM observations from 300 to 773 K confirm that the satellites associated with q⃗1 vanish completely, only at a temperature significantly higher than the CO temperature. This incommensurate modulation has a displacive character and corresponds primarily to a transverse displacive modulation wave of the Lu cations position, as revealed by the high resolution, high angle annular dark field scanning TEM images and in agreement with synchrotron data refinements. Analyses of vacuum-annealed samples converge toward the hypothesis of a new ordering mechanism, associated with a tiny oxygen deviation from the O4 stoichiometry. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000299896900003 |
Publication Date |
2012-02-06 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor  |
3.836 |
Times cited |
24 |
Open Access |
|
| Notes |
Hercules |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:95042 |
Serial |
1095 |
| Permanent link to this record |
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| Author |
Maignan, A.; Lebedev, O.I.; Van Tendeloo, G.; Martin, C.; Hebert, S. |
| Title |
Metal to insulator transition in the n-type hollandite vanadate Pb1.6V8O16 |
Type |
A1 Journal article |
| Year |
2010 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
82 |
Issue |
3 |
Pages |
035122, 1-035122,5 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The transport and magnetic measurements of polycrystalline Pb1.6V8O16 hollandite reveal a concomitant metal to insulator and antiferromagnetic transition at TMI≈140 K. A clear localization is found below TMI, evidenced by a rapid increase in the absolute value of the negative Seebeck coefficient. The structural study by x-ray and transmission electron microscopy confirms the hollandite structure and shows that no structural transition occurs at TMI, ruling out a possible charge orbital ordering. The negative Seebeck coefficient observed from 50 K up to 900 K, with values reaching S=−38 μV K−1 at 900 K, is explained by the electron doping of ∼1.4e− in the V empty t2g orbitals responsible for the bad metal resistivity (ρ900 K∼2 mΩ cm). As this S value is close to that obtained by considering only the spin and orbital degeneracies, it is expected that |S| for such vanadates will not be sensitive at high temperature to the t2g band filling |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000280366300002 |
Publication Date |
2010-07-27 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
10 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 3.836; 2010 IF: 3.774 |
| Call Number |
UA @ lucian @ c:irua:84065 |
Serial |
2009 |
| Permanent link to this record |
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| Author |
Maignan, A.; Martin, C.; Van Tendeloo, G.; Hervieu, M.; Raveau, B. |
| Title |
Size mismatch : a crucial factor for generating a spin-glass insulator in manganites |
Type |
A1 Journal article |
| Year |
1999 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
60 |
Issue |
22 |
Pages |
15214-15219 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
Thr structural, electronic, and magnetic properties of the highly mismatched perovskite oxides, Th(0.35)A(0.65)MnO(3), where Ais for the alkaline earth divalent cations (Ca, Ba, Sr), which are all characterized by the same large tolerance factor (t=0.934), have been investigated by using electron microscopy, electrical resistivity, magnetic susceptibility, and magnetization. It is clearly established that a transition from ferromagnetic metallic towards spin-glass insulator samples is induced as the A-site cationic size mismatch is increased. Moreover, the magnetoresistance (MR) properties of these manganites are strongly reduced for the spin-glass insulators, demonstrating that the A-sire cationic disorder is detrimental for the colossal MR properties. Based on these results, a new electronic and magnetic diagram is established that shows that the A-site disorder, rather than the A-site average cationic size (or t) is the relevant factor for generating spin-glass insulating manganites. [S0163-1829(99)01746-4]. |
| Address |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000084631600039 |
Publication Date |
2002-07-27 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0163-1829;1095-3795; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
75 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 3.836; 1999 IF: NA |
| Call Number |
UA @ lucian @ c:irua:104280 |
Serial |
3038 |
| Permanent link to this record |
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| Author |
Hadermann, J.; Abakumov, A.M.; Gillie, L.J.; Martin, C.; Hervieu, M. |
| Title |
Coupled cation and charge ordering in the CaMn306 tunnel structure |
Type |
A1 Journal article |
| Year |
2006 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
18 |
Issue |
23 |
Pages |
5530-5536 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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| Language |
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Wos |
000241808600021 |
Publication Date |
2006-10-15 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0897-4756;1520-5002; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
33 |
Open Access |
|
| Notes |
Iap V-1 |
Approved |
Most recent IF: 9.466; 2006 IF: 5.104 |
| Call Number |
UA @ lucian @ c:irua:61374 |
Serial |
534 |
| Permanent link to this record |
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| Author |
Gillie, L.J.; Hadermann, J.; Hervieu, M.; Maignan, A.; Martin, C. |
| Title |
Oxygen vacancy ordering in the double-layered Ruddlesden-Popper cobaltite Sm2BaCo2O7-\delta |
Type |
A1 Journal article |
| Year |
2008 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
| Volume |
20 |
Issue |
19 |
Pages |
6231-6237 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
A new oxygen-deficient Ruddlesden−Popper (RP) cobaltite Sm2BaCo2O7−δ (δ ≈ 1.0) has been synthesized and the crystal structure elucidated by Rietveld analysis of X-ray powder diffraction (XRD) data and transmission electron microscopy (TEM). The phase crystallizes in a primitive orthorhombic unit cell, with lattice parameters a = 5.4371(4) Å; b = 5.4405(4) Å and c = 19.8629(6) Å, and space group Pnnm. Contrary to other oxygen-deficient cobalt RP phases, the oxygen vacancies are located in the equatorial positions of the [CoO] layers to give an intralayer structure similar to Sr2Mn2O5, which is not usually observed for cobalt-containing materials. The Sm3+ and Ba2+ cations show a strong preference for distinct sites, with the majority of the larger Ba2+ cations situated in the perovskite block layers and Sm3+ cations predominantly in the rock salt layers. Magnetic susceptibility data demonstrate the strong antiferromagnetic (AFM) character of Sm2BaCo2O7−δ. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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| Language |
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Wos |
000259871500038 |
Publication Date |
2008-09-13 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0897-4756;1520-5002; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
7 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 9.466; 2008 IF: 5.046 |
| Call Number |
UA @ lucian @ c:irua:72946 |
Serial |
2548 |
| Permanent link to this record |
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| Author |
Hervieu, M.; Martin, C.; Maignan, A.; Van Tendeloo, G.; Jirak, Z.; Hejtmanek, J.; Barnabe, A.; Thopart, D.; Raveau, B. |
| Title |
Structural and magnetotransport transitions in the electron-doped Pr1-xSrxMnO3(0.85\leq x\leq1) manganites |
Type |
A1 Journal article |
| Year |
2000 |
Publication |
Chemistry and materials |
Abbreviated Journal |
Chem Mater |
| Volume |
12 |
Issue |
5 |
Pages |
1456-1462 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The exploration of the Mn4+-rich side of the Pr1-xSrxMnO3 system has allowed the extension of the domain of the cubic perovskite, by using a two-step process, combining synthesis under Ar flow at high temperature and O-2 pressure annealing at lower temperature. We show that these Pr-doped cubic perovskites exhibit a coupled structural (cubic-tetragonal) and magnetic (para-antiferro) transition connected with a resistivity jump at the same temperature. The strong interplay between lattice, charges, and spins for these oxides results from the appearance at low temperature of the distorted C-type antiferromagnetic structure. The Pr1-xSrxMnO3 magnetic phase diagram shows, for 0.9 less than or equal to x less than or equal to 1 (i.e., on the Mn4+-rich side), the existence at low temperature of C- and G-type antiferromagnetism. The absence of ferromagnetic-antiferromagnetic competition explains that magnetoresistante properties are not observed in this system, in contrast to Mn4+-rich Ln(1-x)Ca(x)MnO(3) systems. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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| Language |
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Wos |
000087136800039 |
Publication Date |
2002-07-26 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0897-4756;1520-5002; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.466 |
Times cited |
24 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 9.466; 2000 IF: 3.580 |
| Call Number |
UA @ lucian @ c:irua:103454 |
Serial |
3198 |
| Permanent link to this record |
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| Author |
Bhatia, H.; Martin, C.; Keshavarz, M.; Dovgaliuk, I.; Schrenker, N.J.; Ottesen, M.; Qiu, W.; Fron, E.; Bremholm, M.; Van de Vondel, J.; Bals, S.; Roeffaers, M.B.J.; Hofkens, J.; Debroye, E. |
| Title |
Deciphering the role of water in promoting the optoelectronic performance of surface-engineered lead halide perovskite nanocrystals |
Type |
A1 Journal article |
| Year |
2023 |
Publication |
ACS applied materials and interfaces |
Abbreviated Journal |
|
| Volume |
15 |
Issue |
5 |
Pages |
7294-7307 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
| Abstract |
Lead halide perovskites are promising candidates for applicability is limited by their structural instability toward moisture. Although a deliberate addition of water to the precursor solution has recently been shown to improve the crystallinity and optical properties of perovskites, the corresponding thin films still do not exhibit a near-unity quantum yield. Herein, we report that the direct addition of a minute amount of water to post-treated substantially enhances the stability while achieving a 95% photoluminescence quantum yield in a NC thin film. We unveil the mechanism of how moisture assists in the formation of an additional NH4Br component. Alongside, we demonstrate the crucial role of moisture in assisting localized etching of the perovskite crystal, facilitating the partial incorporation of NH4+, which is key for improved performance under ambient conditions. Finally, as a proof-of-concept, the application of post-treated and watertreated perovskites is tested in LEDs, with the latter exhibiting a superior performance, offering opportunities toward commercial application in moisture-stable optoelectronics. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000931729400001 |
Publication Date |
2023-01-27 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
1944-8244 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.5 |
Times cited |
3 |
Open Access |
Not_Open_Access |
| Notes |
H.B. would like to express her sincere gratitude to Dr. Peter Erk (formerly BASF SE, Germany) for very insightful discussions. The authors acknowledge financial support from the Research Foundation-Flanders (FWO grant numbers S002019N, 1514220N, G.0B39.15, G.0B49.15, G098319N, and ZW15_09-GOH6316) , the KU Leuven Research Fund (C14/19/079, iBOF-21-085 PERSIST, and STG/21/010) , the Flemish government through long-term structural funding Methusalem (CASAS2, Meth/15/04) , the Hercules Founda-tion (HER/11/14) , and the ERC through the Marie Curie ITN iSwitch Ph.D. fellowship to H.B. (grant number 642196) . C.M. acknowledges the financial support from grants PID2021-128761OA-C22 funded by MCIN/AEI/10.13039/501100011033 by the ?European Union? and SBPLY/21/180501/000127 funded by JCCM and by the EU through Fondo Europeo de Desarollo Regional? (FEDER) . Martin Bremholm and Martin Ottesen acknowledge funding from the Danish Council for Independent Research, Natural Sciences, under the Sapere Aude program (grant no. 7027-00077B) and VILLUM FONDEN through the Centre of Excellence for Dirac Materials (grant no. 11744) . Affiliation with the Center for Integrated Materials Research (iMAT) at Aarhus University is gratefully acknowledged.-N.J.S. acknowledges financial support from the research foundation Flanders (FWO) through a postdoctoral fellowship (FWO grant no. 1238622N) . S.B. acknowledges financial support from the European Commission by the ERC Consolidator grant REALNANO (no. 815128) . |
Approved |
Most recent IF: 9.5; 2023 IF: 7.504 |
| Call Number |
UA @ admin @ c:irua:195375 |
Serial |
7293 |
| Permanent link to this record |
