Gunter Luepke

Learn More
We report on the quasi-particle dynamics of the charge/orbital ordered (COO) and ferromagnetic clusters in the optimally doped manganite, La0.7Ca0.3MnO3 (LCMO) single crystal by time-resolved two-color pump–probe spectroscopy. Pump photons with energies of ∼1.55 and ∼0.21 eV were employed in our transient optical spectroscopy to investigate the percolative(More)
The ferromagnet/oxide interface is key to developing emerging multiferroic and spintronic technologies with new functionality. Here we probe the Fe/MgO interface magnetization, and identify a new exchange bias phenomenon manifested only in the interface spin system, and not in the bulk. The interface magnetization exhibits a pronounced exchange bias, and(More)
The interaction between surface plasmons (SP) and magnetic behavior has generated great research interest due to its potential for future magneto-optical devices with ultra-high sensitivity and ultra-fast switching. Here we combine two surface sensitive effects: magnetic second-harmonic generation (MSHG) and SP to enhance the detection sensitivity of the(More)
Measurements of the O-H and O-D vibrational lifetimes show that the room-temperature hydrogen diffusion rate in rutile TiO2 can be enhanced by 9 orders of magnitude when stimulated by resonant infrared light. We find that the local oscillatory motion of the proton quickly couples to a wag-mode-assisted classical transfer process along the c channel with a(More)
Polarization-selective optical second-harmonic generation (SHG) is applied to monitor nonuniform polarization distributions in centrosymmetric media modulated by an external dc electric field. Two different systems are investigated: first, optical SHG from a Au-Si(100) Schottky Barrier is shown to be a direct probe of the electric field polarity near such a(More)
The reversal process of the Fe interface layer magnetization in Fe/AlGaAs heterostructures is measured directly using magnetization-induced second-harmonic generation, and is compared with the reversal of the bulk magnetization as obtained from magneto-optic Kerr effect. The switching characteristics are distinctly different due to interface-derived(More)
We solve this long-standing problem theoretically by recognizing that the ranks of the tensors that describe the surface and bulk second-order nonlinear susceptibilities differ in this class of media. We show that this implies that the phenomenologies of the anisotropic optical second-harmonic (SH) responses of the two sources differ for all possible(More)
The dependence of the intrinsic Gilbert damping parameter α(0) on the spin-orbital coupling strength ξ is investigated in L1(0) ordered FePd(1-x) Pt(x) films by time-resolved magneto-optical Kerr effect measurements and spin-dependent ab initio calculations. Continuous tuning of α(0) over more than one order of magnitude is realized by changing the Pt/Pd(More)
Vibrational lifetimes of hydrogen and deuterium related bending modes in semiconductors are measured by transient bleaching spectroscopy and high-resolution infrared absorption spectroscopy. We find that the vibrational lifetimes follow a universal frequency-gap law; i.e., the decay time increases exponentially with increasing decay order, with values(More)
We studied the spatial intensity profile of an ultrashort laser pulse passing through a laser beam shaping system, which uses diffractive optical elements to reshape a Gaussian beam profile into a flat-topped distribution. Both dispersion and nonlinear self-phase modulation are included in the theoretical model. Our calculation shows that this system works(More)