212 research outputs found
Large Magnetoresistance Effects in CoAsO with a Ferromagnetic-Antiferromagnetic Transition
A large magnetoresistance (MR) effect was observed in the layered compounds
NdCoAsO and SmCoAsO, in which ferromagnetically ordered itinerant-electrons of
Co are sandwiched by localized 4-electrons of , below
ferromagnetic-antiferromagnetic transition (FAFT) temperature as
observed in other FAFT compounds. In SmCoAsO, the large MR effect is also
observed up to the Curie temperature , and it is found to be
originating in the presence of another antiferromagnetic phase in the
low-magnetic field region of the ferromagnetic phase.Comment: 5 pages, 5 figure
Dynamics of Bound Magnon Pairs in the Quasi-One-Dimensional Frustrated Magnet LiCuVO_4
We report on the dynamics of the spin-1/2 quasi-one-dimensional frustrated
magnet LiCuVO measured by nuclear spin relaxation in high magnetic
fields 10--34 T, in which the ground state has spin-density-wave order. The
spin fluctuations in the paramagnetic phase exhibit striking anisotropy with
respect to the magnetic field. The transverse excitation spectrum probed by
V nuclei has an excitation gap, which increases with field. On the other
hand, the gapless longitudinal fluctuations sensed by Li nuclei grow with
lowering temperature, but tend to be suppressed with increasing field. Such
anisotropic spin dynamics and its field dependence agree with the theoretical
predictions and are ascribed to the formation of bound magnon pairs, a
remarkable consequence of the frustration between ferromagnetic nearest
neighbor and antiferromagnetic next-nearest-neighbor interactions.Comment: 7 pages, 6 figure
Spin-1/2 Triangular-Lattice Heisenberg Antiferromagnet with √3 × √3-Type Distortion --Behavior around the Boundaries of the Intermediate Phase
The S = 1/2 triangular-lattice Heisenberg antiferromagnet with distortion is investigated by the numerical-diagonalization method. The examined distortion type is √3 × √3. We study the case when the distortion connects the undistorted triangular lattice and the dice lattice. For the intermediate phase reported previously in this system, we obtain results of the boundaries of the intermediate phase for a larger system than those in the previous report and examine the system size dependence of the boundaries in detail. We also report the specific heat of this system, which shows a marked peak structure related to the appearance of the intermediate state
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