In this article we have studied nonequilibrium phase transition into the pseudogap state. Th three-pulse experiments have revealed short correlation range of the dynamical state and individual character of the quasiparticle relaxation. Energy required for nonthermal destruction of the pseudogap scales linearly with the gap. This is explained with the model which accounts for subgap phonons generation.
B.04 Guest lecture
COBISS.SI-ID: 28974631Co-organization of scientific meeting; The scope of the meeting is to focus on new approaches to theory of ultrafast phenomena in correlated electronic systems as well as related experimental observation. This covers fundamental problems of hot carrier relaxation in strange metals, collective phenomena and quasi-particle relaxation in superconductors, charge and spin density way systems, excitonic and Mott insulators and related materials.
B.01 Organiser of a scientific meeting
COBISS.SI-ID: 29106983The richness of the iron-based-pnictides phase diagram is reflected also in the transient optical response. Systematic investigations of the photo excited quasi-particle relaxation in electron doped 1111 and 122 iron-based pnictides by all-optical methods revealed information regarding the electron phonon coupling, charge gap in the spin-density wave (SDW) state, gaps in the superconducting state and nematic fluctuations in the normal state. Another interesting aspect of the iron-based-pnictides is the presence of rare earth ions in the crystal structure enabling study of a coexistence of the ferromagnetic order of the rare-earth f-orbital spins with the superconducting order of the Fe-d-bands carriers. We briefly review the all-optical relaxation dynamics results in various parts of the phase diagram with emphasis on our recent results concerning the antiferromagnetic(SDW) stateand the rare-earth f-orbital spin dynamics in Eu based 122 compounds.
B.04 Guest lecture
COBISS.SI-ID: 29611047A unique insight into the dynamics of symmetry breaking (SB) can be obtained from real-time experiments on “freely evolving” phase transitions in condensed matter systems. Such experiments offer analogies with other time-evolving systems in cosmology and elementary particle collisions, and even in collective social phenomena. Charge ordered materials and superconductors are two examples where different symmetries are broken on femtosecond timescales which can be investigated with femtosecond laser spectroscopy techniques. The trajectories through the transition can be investigated via the response of single particle (fermionic) and collective (bosonic) excitations with very high temporal resolution. This enables us to observe new phenomena, such as coherent oscillations of the order parameter through the transition and dispersive Higgs-like particle emission resulting from domain wall annihilation. Weakly interacting massive particles (phonons) which interact with the order parameter offer analogies with dark matter existing prior to the transition. Beyond standard theory, non-equilibrium trajectories to hidden states of matter are also observed under conditions where the fermionic and bosonic excitations are far out of equilibrium, reaching states which are unreachable under adiabatic conditions.
B.04 Guest lecture
COBISS.SI-ID: 27822631The aim of the conference entitled “Photoinduced phase transitions and cooperative phenomena - 5” (PIPT5) was to bring together leading scientists in the field to present their most recent results, and through the exchange of ideas consider new challenges and develop new ideas in this rapidly developing field. Since the first PIPT meeting, the field has grown steadily and some very rapid developments have taken place in the last few years. As time-resolved spectroscopy has become mainstream and has been accepted and understood by the wider community, new opportunities arise. The recent rapid expansion of new experimental techniques on one hand, and new theory developments of nonequilibrium systems on the other, together with the discovery of new systems offering cooperative phenomena, the meeting was an exciting one. The main topics covered by the conference were: New phenomena in nonequilibrium collective behavior, New materials exhibiting photoinduced phase transitions and cooperative phenomena, New time-resolved experimental technologies for studies of nonequilibrium phenomena, Theoretical developments in nonequilibrium phase transitions.
B.02 Presiding over the programming board of a conference
COBISS.SI-ID: 27772967