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Université de Fribourg

Uniaxial strain-induced phase transition in the 2D topological semimetal IrTe2

Nicholson, Christopher W. ; Rumo, Maxime ; Pulkkinen, Aki ; Kremer, Geoffroy ; Salzmann, Björn ; Mottas, Marie-Laure ; Hildebrand, Baptiste ; Jaouen, Thomas ; Kim, Timur K. ; Mukherjee, Saumya ; Ma, KeYuan ; Muntwiler, Matthias ; von Rohr, Fabian O. ; Cacho, Cephise ; Monney, Claude

In: Communications Materials, 2021, vol. 2, no. 1, p. 25

Strain is ubiquitous in solid-state materials, but despite its fundamental importance and technological relevance, leveraging externally applied strain to gain control over material properties is still in its infancy. In particular, strain control over the diverse phase transitions and topological states in two-dimensional transition metal dichalcogenides remains an open challenge. Here, we...

Université de Fribourg

Unveiling the Semimetallic Nature of 1$T$-TiSe$_2$ by Doping its Charge Density Wave

Jaouen, Thomas ; Rumo, Maxime ; Hildebrand, Baptiste ; Mottas, Marie-Laure ; Nicholson, Christopher W. ; Kremer, Geoffroy ; Salzmann, Björn ; Vanini, Fabiano ; Barreteau, C. ; Giannini, E. ; Beck, Hans-Peter ; Aebi, Philipp ; Monney, Claude

The semimetallic or semiconducting nature of the transition metal dichalcogenide 1$T$-TiSe$_2$ remains under debate after many decades mainly due to the fluctuating nature of its 2 x 2 x 2 charge-density-wave (CDW) phase at room- temperature. In this letter, using angle-resolved photoemission spectroscopy, we unambiguously demonstrate that the 1$T$-TiSe$_2$ normal state is semimetallic with ...

Université de Fribourg

Insensitivity of the striped charge orders in ${\mathrm{IrTe}}_{2}$ to alkali surface doping implies their structural origin

Rumo, Maxime ; Pulkkinen, Aki ; Salzmann, Björn ; Kremer, Geoffroy ; Hildebrand, Baptiste ; Ma, Keyan ; von Rohr, Fabian ; Nicholson, Christopher W. ; Jaouen, Thomas ; Monney, Claude

In: Physical Review Materials, 2021, vol. 5, no. 7, p. 074002

We present a combined angle-resolved photoemission spectroscopy and low-energy electron diffraction (LEED) study of the prominent transition metal dichalcogenide IrTe2 upon potassium (K) deposition on its surface. Pristine IrTe2 undergoes a series of charge-ordered phase transitions below room temperature that are characterized by the formation of stripes of Ir dimers of different...

Université de Fribourg

Misfit layer compounds: a platform for heavily doped 2D transition metal dichalcogenides

Leriche, Raphaël T. ; Palacio‐Morales, Alexandra ; Campetella, Marco ; Tresca, Cesare ; Sasaki, Shunsuke ; Brun, Christophe ; Debontridder, François ; David, Pascal ; Arfaoui, Imad ; Šofranko, Ondrej ; Samuely, Tomas ; Kremer, Geoffroy ; Monney, Claude ; Jaouen, Thomas ; Cario, Laurent ; Calandra, Matteo ; Cren, Tristan

In: Advanced Functional Materials, 2020, p. 2007706

Transition metal dichalcogenides (TMDs) display a rich variety of instabilities such as spin and charge orders, Ising superconductivity, and topological properties. Their physical properties can be controlled by doping in electric double‐layer field‐effect transistors (FET). However, for the case of single layer NbSe2, FET doping is limited to ≈1 × 1014 cm−2, while a somewhat larger...

Université de Fribourg

Structural phase transition and bandgap control through mechanical deformation in layered semiconductors 1T–ZrX2 (X = S, Se)

Martino, Edoardo ; Santos-Cottin, David ; Le Mardelé, Florian ; Semeniuk, Konstantin ; Pizzochero, Michele ; Čerņevičs, Kristia̅ns ; Baptiste, Benoît ; Delbes, Ludovic ; Klotz, Stefan ; Capitani, Francesco ; Berger, Helmuth ; Yazyev, Oleg V. ; Akrap, Ana

In: ACS Materials Letters, 2020, vol. 2, no. 9, p. 1115–1120

Applying elastic deformation can tune a material’s physical properties locally and reversibly. Spatially modulated lattice deformation can create a bandgap gradient, favoring photogenerated charge separation and collection in optoelectronic devices. These advantages are hindered by the maximum elastic strain that a material can withstand before breaking. Nanomaterials derived by exfoliating...

Université de Fribourg

Examining the surface phase diagram of ${\mathrm{IrTe}}_{2}$ with photoemission

Rumo, Maxime ; Nicholson, Christopher W. ; Pulkkinen, Aki ; Hildebrand, Baptiste ; Kremer, Geoffroy ; Salzmann, Björn ; Mottas, Marie-Laure ; Ma, K. Y. ; Wong, E. L. ; Man, M. K. L. ; Dani, K. M. ; Barbiellini, B. ; Muntwiler, Matthias ; Jaouen, Thomas ; Rohr, F. O. von ; Monney, Claude

In: Physical Review B, 2020, vol. 101, no. 23, p. 235120

In the transition metal dichalcogenide IrTe2, low-temperature charge-ordered phase transitions involving Ir dimers lead to the occurrence of stripe phases of different periodicities, and nearly degenerate energies. Bulk-sensitive measurements have shown that, upon cooling, IrTe2 undergoes two such first-order transitions to (5×1×5) and (8×1×8) reconstructed phases at Tc1∼280 K and...

Université de Fribourg

Preferential out-of-plane conduction and quasi-one-dimensional electronic states in layered 1T-TaS 2

Martino, E. ; Pisoni, A. ; Ćirić, L. ; Arakcheeva, A. ; Berger, H. ; Akrap, Ana ; Putzke, C. ; Moll, P. J. W. ; Batistić, I. ; Tutiš, E. ; Forró, László ; Semeniuk, K.

In: npj 2D Materials and Applications, 2020, vol. 4, no. 1, p. 1–9

Layered transition metal dichalcogenides (TMDs) are commonly classified as quasi-two-dimensional materials, meaning that their electronic structure closely resembles that of an individual layer, which results in resistivity anisotropies reaching thousands. Here, we show that this rule does not hold for 1T-TaS2—a compound with the richest phase diagram among TMDs. Although the onset of ...

Université de Fribourg

Role of a higher-dimensional interaction in stabilizing charge density waves in quasi-one-dimensional ${\mathrm{NbSe}}_{3}$ revealed by angle-resolved photoemission spectroscopy

Nicholson, Christopher W. ; Schwier, Eike Fabian ; Shimada, K. ; Berger, Helmuth ; Hoesch, M. ; Berthod, C. ; Monney, Claude

In: Physical Review B, 2020, vol. 101, no. 4, p. 045412

We revisit charge density wave (CDW) behavior in the archetypal quasi-one- dimensional (quasi-1D) material NbSe3 by high-resolution angle-resolved photoemission spectroscopy measurements utilizing a microfocused laser with a photon energy of 6.3 eV. We present a detailed view of the electronic structure of this complex multiband system and unambiguously resolve CDW gaps at the Fermi level ...

Université de Fribourg

S-layer protein-AuNP systems for the colorimetric detection of metal and metalloid ions in water

Jung, J. ; Lakatos, Mathias ; Bengs, S. ; Matys, S. ; Raff, J. ; Blüher, A. ; Cuniberti, G.

In: Colloids and Surfaces B: Biointerfaces, 2019, vol. 183, p. 110284

Bacterial surface layer proteins (S-layer) possess unique binding properties for metal ions. By combining the binding capability of S-layer proteins with the optical properties of gold nanoparticles (AuNP), namely plasmonic resonance, a colorimetric detection system for metal and metalloid ions in water was developed. Eight S-layer proteins from different bacteria species were used for the...

Université de Fribourg

DNA‐mediated self‐assembly of plasmonic antennas with a single quantum dot in the hot spot

Nicoli, Francesca ; Zhang, Tao ; Hübner, Kristina ; Jin, Boyuan ; Selbach, Florian ; Acuna, Guillermo P. ; Argyropoulos, Christos ; Liedl, Tim ; Pilo-Pais, and Mauricio

In: Small, 2019, vol. 15, no. 26, p. 1804418

DNA self‐assembly is a powerful tool to arrange optically active components with high accuracy in a large parallel manner. A facile approach to assemble plasmonic antennas consisting of two metallic nanoparticles (40 nm) with a single colloidal quantum dot positioned at the hot spot is presented here. The design approach is based on DNA complementarity, stoichiometry, and steric hindrance...