Temperature and fluence dependence of the transient photoinduced reflectivity and the magnetooptical Kerr angle was measured in two Pr0.6Ca0.4MnO3 thin films subject to tensile and compressive substrate-induced strain. A photoinduced transient ferromagnetic metallic (TFM) phase is found to form below 60 and 40 K in the substrate-strained and substrate-compressed films, respectively.
COBISS.SI-ID: 23175207
The coupling of phonons with collective modes and single-particle gap excitations associated with one-(1d) and two-directional (2d) electronically driven charge-density wave (CDW) ordering in metallic RTe3 are investigated as a function of rare-earth ion chemical pressure (R = Tb;Dy;Ho) using femtosecond pump-probe spectroscopy. From the T dependence of the CDW gap and the amplitude mode, we find that while the transition to a 1d-CDW ordered state at Tc1 initially proceeds in an exemplary mean- field-like fashion, below Tc1, gap is depressed and departs from the mean-?eld behavior.
COBISS.SI-ID: 22302759
We use ultrashort intense laser pulses to study superconducting state vaporization dynamics in La2-xSrxCuO4 on the femtosecond time scale. The energy density required to vaporize the superconducting state is significantly greater than the condensation energy density, indicating that the quasiparticles share a large amount of energy with the boson glue bath. Considering in detail both spin and lattice energy relaxation pathways which take place on the relevant time scale of ~10 ps, the experiments appear to favor phonon-mediated pair-breaking mechanisms over spin-mediated pair breaking.
COBISS.SI-ID: 22209063
We use femtosecond spectroscopy to investigate the quasiparticle relaxation and lowenergy electronic structure in a pnictide superconductor with Tc = 49.5 K. Multiple relaxation processes are evident, with distinct superconducting state quasiparticle recombination dynamics exhibiting a T-dependent superconducting gap, and a clear ‘‘pseudogaplike’’ feature with an onset above 180 K indicating the existence of a temperature-independent gap above Tc. The superconducting and pseudogap components show saturation as a function of fluence with saturation fluences 4 and 40 uJ/cm2, respectively.
COBISS.SI-ID: 22500391
We present a systematic study of the electronic- and spin-excitation dynamics associated with the sequence of spin- and orbital-ordering phase transformations in the complex vanadates YVO3 and GdVO3 with ultrafast optical pump-probe reflectance spectroscopy. Relaxation dynamics occurs on a different time scale for each of the ordering transitions, which enables us to unambiguously associate the critical behavior in the dynamics with the observed ordering phenomena.
COBISS.SI-ID: 23384615