The field of semiconductor spintronics explores spin-related quantum relativistic phenomena in solid-state systems. Spin transistors and spin Hall effects have been two separate leading directions of research in this field. We have combined the two directions by realizing an all-semiconductor spin Hall effect transistor. The device uses diffusive transport and operates without electrical current in the active part of the transistor. We demonstrate a spin AND logic function in a semiconductor channel with two gates. Our study shows the utility of the spin Hall effect in a microelectronic device geometry, realizes the spin transistor with electrical detection directly along the gated semiconductor channel, and provides an experimental tool for exploring spin Hall and spin precession phenomena in an electrically tunable semiconductor layer.

Tetragonal CuMnAs is an antiferromagnetic material with favourable properties for applications in spintronics. Using a combination of neutron diffraction and x-ray magnetic linear dichroism, we determine the spin axis and magnetic structure in tetragonal CuMnAs, and reveal the presence of an interfacial uniaxial magnetic anisotropy. From the temperature-dependence of the neutron diffraction intensities, the Néel temperature is shown to be (480 ± 5) K. Ab initio calculations indicate a weak anisotropy in the (ab) plane for bulk crystals, with a large anisotropy energy barrier between in-plane and perpendicular-to-plane directions.

We report single-color, time resolved magneto-optical measurements in ferromagnetic semiconductor (Ga,Mn)As. We demonstrate coherent optical control of the magnetization precession by applying two successive ultrashort laser pulses. The magnetic field and temperature dependent experiments reveal the collective Mnmoment nature of the oscillatory part of the time-dependent Kerr rotation, as well as contributions to the magneto-optical signal that are not connected with the magnetization dynamics.The lasting demand for increased speed of writing and retrieving magnetically stored information in computer hard drives stimulated an intense research of ultrafast magnetization dynamics. In particular, the ultrafast control of magnetization by laser pulses has gained a significant attention recently [1]. Initially, the research was focused mainly on ferromagnetic metals and half-metals where the impact of ultrashort (subpicosecond) laser pulses can lead to demagnetization [2], magnetization rotation [3] or even to modification of magnetic structure [4]. More recently, also the investigation of diluted magnetic semiconductors (DMSs) has started. The most intensively studied example of DMSs is (Ga,Mn)As where the ferromagnetic coupling between Mn local-moments is meadiated by spin-polarized valence band holes [5]. In the last few years, not only the ultrafast demagnetization [6] but also the ultrafast enhancement of ferromagnetism [7], the complete reversal of magnetic hysteresis loop [8] and the laser-induced precession of magnetization [9][10][11] were demonstrated in (Ga,Mn)As.Ultrashort laser pulses can be also used for coherent control of the spin precession. In this experiment the sample is excited by pairs of pump pulses. Each pump pulse generates a transient precession of magnetization vector and their temporal separation (i.e., the mutual phase difference between the corresponding magnetization precessions) determines if they superimpose constructively or destructively. Coherent control of magnetization was demonstrated in various types of magnetic materials -ferrimagnetic garnet [1], antiferromagnetic orthoferrites [1], half-metalic ferromagnetic CrO 2 [12], and paramagnetic (Cd,Mn)Te [13].In this paper, we report on the coherent control of magnetization precession in ferromagnetic (Ga,Mn)As. The experiments were performed on an annealed 50 nm thick ferromagnetic (Ga,Mn)As film with nominal Mn doping of 7% and the Curie temperature T C ≈ 160 K, which was grown by the low temperature molecular beam epitaxy (LT-MBE) on a GaAs(001) substrate. The sample exhibits in-plane easy axis behavior typical for stressed (Ga,Mn)As layers grown on GaAs substrates. The external magnetic field (generated by an a) Electronic mail: nemec@karlov.mff.cuni.cz 1

Time-and polarization-resolved differential transmission measurements employing same and oppositely circularly polarized 150 fs optical pulses are used to investigate spin characteristics of conduction band electrons in bulk GaAs at 295 K. Electrons and holes with densities in the 2 ϫ 10 16 cm −3-10 18 cm −3 range are generated and probed with pulses whose center wavelength is between 865 and 775 nm. The transmissivity results can be explained in terms of the spin sensitivity of both phase-space filling and many-body effects ͑band-gap renormalization and screening of the Coulomb enhancement factor͒. For excitation and probing at 865 nm, just above the band-gap edge, the transmissivity changes mainly reflect spin-dependent phase-space filling which is dominated by the electron Fermi factors. However, for 775 nm probing, the influence of many-body effects on the induced transmission change are comparable with those from reduced phase space filling, exposing the spin dependence of the many-body effects. If one does not take account of these spindependent effects one can misinterpret both the magnitude and time evolution of the electron spin polarization. For suitable measurements we find that the electron spin relaxation time is 130 ps.

Non-collinear antiferromagnets are revealing many unexpected phenomena and they became crucial for the field of antiferromagnetic spintronics. To visualize and prepare a well-defined domain structure is of key importance. The spatial magnetic contrast, however, remains extraordinarily difficult to be observed experimentally. Here, we demonstrate a magnetic imaging technique based on a laser induced local thermal gradient combined with detection of the anomalous Nernst effect. We employ this method in one the most actively studied representatives of this class of materials—Mn3Sn. We demonstrate that the observed contrast is of magnetic origin. We further show an algorithm to prepare a well-defined domain pattern at room temperature based on heat assisted recording principle. Our study opens up a prospect to study spintronics phenomena in non-collinear antiferromagnets with spatial resolution.