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UID:69e22de68774b
DTSTART:20260205T090000Z
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TRANSP:OPAQUE
LOCATION:Auditorium
SUMMARY:ICFO | IGOR TYULNEV
CLASS:PUBLIC
DESCRIPTION:This work presents the experiments and results on the applicati
 on of mid-infrared laser sources towards condensed matter systems for the 
 study and control of manybody interactions within material phases and at p
 hase boundaries. Utilizing the decades in know-how and development of inte
 nse\, few-cycle waveforms at high repetition rates\, the here demonstrated
  applications leverage the mid-infrared wavelengths to study and control s
 trong-field phenomena at ultrafast time-scales and across phase transition
 s. To this end non-linear techniques are employed to extend the source cap
 abilities towards a variety of driving and probing wavelengths\, meanwhile
  tailoring spin-angular momentum multi-color beams as driving fields with 
 unique patterns. With strong-field driven dynamics happening at sub-cycle 
 time scales\, techniques such as high harmonic generation (HHG) are applie
 d to a variety of materials which undergo electronic and structural transi
 tions. For bulk transition metal dichalcogenides\, as the investigated MoS
 2\, the induced spatial and temporal symmetry breaking from a tailored tre
 foil-shaped strong-field allowed the detection of valley polarization\, i.
 e. a carrier population imbalance between neighboring bandgap extrema. The
  specific control of the energy bands at these sites\, first\, allows the 
 realization of a valley switch to be used for optical computing\, and seco
 nd\, realizes a hybrid system of light and matter with band topology akin 
 to the Haldane model\, which paves the way towards field-induced and contr
 olled topological phase transitions in two-dimensional materials. Furtherm
 ore\, the field-induced currents and the emerging harmonics are used to pr
 obe the potential landscape of the lattice and therefore\, simultaneously 
 detect signatures of the crystal and band structure encoded in a static sp
 ectrum. Interference within the spectra further reveal the underlying elec
 tron-hole dynamics and timings. In high-temperature superconducting cerami
 cs like YBCO\, the temperature induced changes in electronic properties ar
 e also sensitively detected via HHG\, even for more elusive material phase
 s. Meanwhile higher order transitions like the correlated charge density w
 ave (CDW) phase shows a mixture of electronic and structural changes in th
 e HHG crystallography as investigated in TiSe2. The macroscopic and nonlin
 ear approach yields major changes in the harmonic spectra even from small 
 changes in e.g. atom displacement and identifies phase anisotropies which 
 eluded conventional or microscopic techniques.\n Thursday\, February 5\, 1
 0:00 h. ICFO Auditorium \nThesis Director: Prof. Dr. Jens Biegert
DTSTAMP:20260417T125606Z
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