Publications de Andreas Helmut Christian Mann

Coherent generation of symmetry-forbidden phonons by light-induced electron-phonon interactions in magnetite

Frank van Mourik, Oleg Yazyev, Christopher Alexander Arrell, Fabrizio Carbone, Andreas Helmut Christian Mann, Edoardo Baldini, Simone Borroni

Symmetry breaking across phase transitions often causes changes in selection rules and emergence of optical modes which can be detected via spectroscopic techniques or generated coherently in pump-probe experiments. In second-order or weakly first-order tr ...

Amer Physical Soc2017

Clocking the onset of bilayer coherence in a high-Tc cuprate

Frank van Mourik, Christopher Alexander Arrell, Dragan Mihailovic, Fabrizio Carbone, Andreas Helmut Christian Mann, Edoardo Baldini

In cuprates, a precursor state of superconductivity is speculated to exist above the critical temperature T-c. Here we show via a combination of far-infrared ellipsometry and ultrafast broadband optical spectroscopy that signatures of such a state can be o ...

Amer Physical Soc2017

Real-Time Observation of Phonon-Mediated σ−π Interband Scattering in MgB2

Fabrizio Carbone, Andreas Helmut Christian Mann, Edoardo Baldini, Simone Borroni, Ting Tan

In systems having an anisotropic electronic structure, such as the layered materials graphite, graphene, and cuprates, impulsive light excitation can coherently stimulate specific bosonic modes, with exotic consequences for the emergent electronic properti ...

2017

A versatile setup for ultrafast broadband optical spectroscopy of coherent collective modes in strongly correlated quantum systems

Frank van Mourik, Christopher Alexander Arrell, Fabrizio Carbone, Andreas Helmut Christian Mann, Edoardo Baldini, Simone Borroni

A femtosecond pump-probe setup is described that is optimised for broadband tran- sient reflectivity experiments on solid samples over a wide temperature range. By combining high temporal resolution and a broad detection window, this apparatus can investig ...

2016

Probing the coupling between a doublon excitation and the charge-density wave in TaS2 by ultrafast optical spectroscopy

Helmuth Berger, Arnaud Magrez, Ahmad Odeh, Fabrizio Carbone, Andreas Helmut Christian Mann, Edoardo Baldini

Recently, the switching between the different charge-ordered phases of 1T-TaS2 has been probed by ultrafast techniques, revealing unexpected phenomena such as "hidden" metastable states and peculiar photoexcited charge patterns. Here, we apply broadband pu ...

Amer Physical Soc2016

Probing the electron-phonon interaction in correlated systems with coherent lattice fluctuation spectroscopy

Frank van Mourik, Christopher Alexander Arrell, Fabrizio Carbone, Kazimierz Conder, Andreas Helmut Christian Mann, Edoardo Baldini

Tailoring the properties of correlated oxides is accomplished by chemical doping, pressure, temperature, or magnetic field. Photoexcitation is a valid alternative to reach out-of-equilibrium states otherwise inaccessible. Here, we quantitatively estimate t ...

Amer Physical Soc2015

Ultrafast Broadband Spectroscopy on Correlated Materials

Andreas Helmut Christian Mann

This thesis deals with femtosecond broadband spectroscopy in the visible regime, which is used to study strongly correlated electron systems. The materials that were studied are high-temperature cuprate superconductors of various dopings and the charge-den ...

EPFL2015

Coupling of a high-energy excitation to superconducting quasiparticles in a cuprate from coherent charge fluctuation spectroscopy

Majed Chergui, Ahmad Odeh, Fabrizio Carbone, Andreas Helmut Christian Mann, Mariateresa Scarongella

Dynamical information on spin degrees of freedom of proteins or solids can be obtained by NMR and electron spin resonance. A technique with similar versatility for charge degrees of freedom and their ultrafast correlations could move the understanding of s ...

National Academy of Sciences2013

Ultrafast structural and electronic dynamics of the metallic phase in a layered manganite

Fabrizio Carbone, Andreas Helmut Christian Mann, Luca Piazza

The transition between different states in manganites can be driven by various external stimuli. Controlling these transitions with light opens the possibility to investigate the microscopic path through which they evolve. We performed femtosecond (fs) tra ...

2013

Investigating pairing interactions with coherent charge fluctuation spectroscopy

Majed Chergui, Ahmad Odeh, Fabrizio Carbone, Andreas Helmut Christian Mann

It has been recently demonstrated that a pump pulse can generate coherent charge fluctuations in a superconductor through a stimulated Raman process [Mansart, et al., Proc. Natl. Acad. Sci. USA 110, 4539 (2013)]. Here, we present a tutorial review of the b ...

Springer Verlag2013