Femtosecond control of electric currents at the interfaces of metallic ferromagnetic heterostructures

The idea to utilize not only the charge but also the spin of electrons in the operation of electronic devices has led to the development of spintronics, causing a revolution in how information is stored and processed. A novel advancement would be to develop ultrafast spintronics using femtosecond laser pulses. Employing terahertz (10$^{12}$ Hz) emission spectroscopy, we demonstrate optical generation of spin-polarized electric currents at the interfaces of metallic ferromagnetic heterostructures at the femtosecond timescale. The direction of the photocurrent is controlled by the helicity of the circularly polarized light. These results open up new opportunities for realizing spintronics in the unprecedented terahertz regime and provide new insights in all-optical control of magnetism.Comment: 3 figures and 2 tables in the main tex

Theory for the nonlinear optical response of quantum-well states in ultrathin films

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Magnetic-field-induced biaxiality in an antiferroelectric liquid crystal

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Noncontact liquid-crystal alignment by supra-molecular amplification of nanogrooves

Groovy surfaces: The small increase in π-electronic character that results from the change from a phenyl- to a naphthalene-functionalized optical switch can have significant consequences. The latter creates a well-defined, grooved surface (see picture), which has been prepared by utilizing a method of noncontact alignment-layer construction. Such a process for liquid-crystal alignment, which is based on a hierarchical process, does not necessitate the use of a clean room

Phasons and broken symmetries in ferroelectric liquid-crystals

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Measurement of the dynamic surface excess in an overflowing cylinder by neutron reflection

Neutron reflection has been used to measure the dynamic surface concentration, Γdyn, of the cationic surfactant CTAB in an overflowing cylinder (OFC). This is the first direct measurement of Γdyn for a surfactant at an expanding liquid surface. Γdyn was measured for bulk concentrations between 1.8 and 0.125 mM, corresponding to areas per molecule of 42 to >300 Å2. Careful account had to be taken of the curvature of the surface in establishing calibration procedures. Γdyn was less than the equilibrium surface concentration Γe at all concentrations below the cmc but approached Γe at bulk concentrations well above the cmc, as expected for an expanding surface. Ellipsometry has been used previously to measure the coefficient of ellipticity of surfactant solutions in an OFC. The neutron reflection data were used to calibrate the ellipticity of the surface in terms of Γdyn, and ellipsometry was then used to map changes in Γdyn across the surface of the OFC with a precision of 2 × 10-8 mol m-2. The ellipticity can also be calibrated against Γe for static solutions, and this calibration curve can be used to calculate Γdyn from the dynamic ellipticities. The values of Γdyn determined by this indirect route were in excellent agreement with the direct measurements by neutron reflection

Surface-induced transverse magneto-optical Kerr effect

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