Publications de Jens Christian Johannsen

Electron Glass Phase with Resilient Zhang-Rice Singlets in LiCu3O3

Rosario Scopelliti, László Forró, Henrik Moodysson Rønnow, Arnaud Magrez, Krunoslav Prsa, Simon Karl Moser, Paul Gregory Freeman, Jens Christian Johannsen, Gianmarco Gatti, Edoardo Martino

LiCu3O3 is an antiferromagnetic mixed valence cuprate where trilayers of edge -sharing Cu(II)O (3d9) are sandwiched in between planes of Cu(I) (3d10) ions, with Li stochastically substituting Cu(II). Angle resolved photoemission spectroscopy (ARPES) and de ...

Amer Physical Soc2024

Spectroscopic view of ultrafast charge carrier dynamics in single- and bilayer transition metal dichalcogenide semiconductors

Jens Christian Johannsen

The quasiparticle spectra of atomically thin semiconducting transition metal dichalcogenides (TMDCs) and their response to an ultrafast optical excitation critically depend on interactions with the underlying substrate. Here, we present a comparative time- ...

ELSEVIER2021

A novel quasi-one-dimensional topological insulator in bismuth iodide beta-Bi4I4

László Forró, Marco Grioni, Oleg Yazyev, Luca Moreschini, Gabriel Albert Autes, Andrea Pisoni, Jens Christian Johannsen, Wentao Zhang

Recent progress in the field of topological states of matter(1,2) has largely been initiated by the discovery of bismuth and antimony chalcogenide bulk topological insulators (TIs; refs 3-6), followed by closely related ternary compounds(7-16) and predicti ...

Nature Publishing Group2016

Ultrafast Band Structure Control of a Two-Dimensional Heterostructure

Jens Christian Johannsen

The electronic structure of two-dimensional (2D) semiconductors can be significantly altered by screening effects, either from free charge carriers in the material or by environmental screening from the surrounding medium. The physical properties of 2D sem ...

Amer Chemical Soc2016

Nature and topology of the low-energy states in ZrTe5

Marco Grioni, Helmuth Berger, Luca Moreschini, Jens Christian Johannsen

Long known for its peculiar resistivity, showing a thus far unexplained anomalous peak as a function of temperature, ZrTe5 has recently received rising attention in a somewhat different context. While both theoretical and experimental results seem to point ...

Amer Physical Soc2016

Ramifications of optical pumping on the interpretation of time-resolved photoemission experiments on graphene

Marco Grioni, Alberto Crepaldi, Jens Christian Johannsen

In pump-probe time and angle-resolved photoemission spectroscopy (TR-ARPES) experiments the presence of the pump pulse adds a new level of complexity to the photoemission process in comparison to conventional ARPES. This is evidenced by pump-induced vacuum ...

Elsevier Science Bv2015

Electronic Structure of Graphene and Topological Insulators : Frequency and Time-domain Perspectives

Jens Christian Johannsen

The study of the electronic band structure of solids is a central task in materials science. Indeed, knowing a material's band structure is key to an understanding of its macroscopic electronic properties. In recent years, a new class of materials has emer ...

EPFL2015

Engineering the topological surface states in the (Sb2)m−Sb2Te3(m=0–3) superlattice serie

Marco Grioni, Arnaud Magrez, Oleg Yazyev, Helmuth Berger, Alberto Crepaldi, Philippe Bugnon, Simon Karl Moser, Jens Christian Johannsen, Gabriel Albert Autes

We investigate the evolution of both the occupied and unoccupied electronic structure in representative compounds of the infinitely adaptive superlattice series (Sb2)m−Sb2Te3 (m=0–3) by means of angle-resolved photoemission spectroscopy and time-delayed tw ...

Amer Physical Soc2015

Ultrafast electron dynamics in epitaxial graphene investigated with time- and angle-resolved photoemission spectroscopy

Marco Grioni, Alberto Crepaldi, Jens Christian Johannsen

In order to exploit the intriguing optical properties of graphene it is essential to gain a better understanding of the light-matter interaction in the material on ultrashort timescales. Exciting the Dirac fermions with intense ultrafast laser pulses trigg ...

Iop Publishing Ltd2015

Tunable Carrier Multiplication and Cooling in Graphene

Marco Grioni, Alberto Crepaldi, Jens Christian Johannsen

Time- and angle-resolved photoemission measurements on two doped graphene samples displaying different doping levels reveal remarkable differences in the ultrafast dynamics of the hot carriers in the Dirac cone. In the more strongly (n-)doped graphene, we ...

Amer Chemical Soc2015