245 research outputs found

    Imaging of emission patterns in a T-shaped quantum wire laser

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    Spatially and spectrally resolved microscopic images of spontaneous and stimulated emissions are imaged at the mirror facets of a GaAs T-shaped quantum wire laser with high uniformity. Laser emission from the one-dimensional ground state reveals a circular image located at the core of a T-shaped optical waveguide but significantly smaller in area than the low power spontaneous emission from the same waveguide. These images unambiguously allow assignment of all spontaneous and laser emissions to the wire ground state and respective intersecting wells in the structure.Comment: 4 pages, 3 figure

    Spin Excitation in Coupled Honeycomb Lattice Ni2_2InSbO6_6

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    We performed an inelastic neutron scattering experiment on a polycrystalline sample of a helimagnet Ni2_2InSbO6_6 to construct the spin Hamiltonian. Well-defined spin-wave excitation with a band energy of 20 meV was observed below TN=76T_{N} = 76 K. Using the linear spin-wave theory, the spectrum was reasonably reproduced with honeycomb spin layers coupled along the stacking axis (the cc axis). The proposed spin model reproduces the soliton lattice induced by a magnetic field applied perpendicular to the cc axis.Comment: 8 pages, 5 figure

    In-plane anisotropy of the single-qq and multiple-qq ordered phases in the antiferromagnetic metal CeRh2_2Si2_2 unveiled by the bulk measurements under uniaxial stress and neutron scattering

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    We performed magnetization, resistivity, and neutron diffraction measurements under uniaxial stress applied along [1-10] direction on the tetragonal magnet CeRh2_2Si2_2 with commensurate magnetic orders. CeRh2_2Si2_2 has two successive antiferromagnetic (AF) orders in zero magnetic field. The high temperature phase (AF1 phase) has the magnetic modulation wave vector of q=(12,12,0)q = (\frac{1}{2}, \frac{1}{2}, 0), and the low temperature phase (AF2 phase) is characterized by the four qq-vectors of q=(12,12,0),(12,βˆ’12,0),(12,12,12)q = (\frac{1}{2}, \frac{1}{2}, 0), (\frac{1}{2}, -\frac{1}{2}, 0), (\frac{1}{2}, \frac{1}{2}, \frac{1}{2}), and (12,βˆ’12,12)(\frac{1}{2}, -\frac{1}{2}, \frac{1}{2}). By measuring the uniaxial stress dependence of the magnetization, resistivity and the intensities of magnetic Bragg reflections, we confirmed that the AF1 phase has the single-qq magnetic order with two-fold rotational symmetry and the AF2 phase has the multi-qq magnetic order with four-fold rotational symmetry. In order to understand the origin of multi-qq order of CeRh2_2Si2_2, we also performed inelastic neutron scattering measurement on the single crystal samples. We found a magnetic excitation at the transfer energy β„Ο‰βˆΌ\hbar \omega \sim 8 meV. By applying the linear spin-wave theory, we found that the nearest and the next-nearest neighbor exchange interactions on the abab-plane, J1J_1 and J2J_2, are dominant in the AF2 phase. However, the J1J_1-J2J_2 model cannot lift the degeneracy between the single-qq (AF1) and multi-qq (AF2) phases. We suggest that it can be lifted by taking into account the biquadratic interaction derived from the perturbative expansion for the Kondo lattice Hamiltonian. [S. Hayami et al., Phys. Rev. B 95, 224424 (2017).Comment: 7 pages, 7 figure
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