195 research outputs found
Origin of modulated phases and magnetic hysteresis in TmB_4
We investigate the low temperature magnetic phases in TmB_4, a metallic
quantum magnet on the geometrically frustrated Shastry-Sutherland lattice,
using co-ordinated experimental and theoretical studies. Our results provide an
explanation for the appearance of the intriguing fractional plateau in TmB_4
and accompanying magnetic hysteresis. Together with observation of the bump in
the half-plateau, our results support the picture that the magnetization
plateau structure in TmB_4 is strongly influenced by the zero-field modulated
phases. We present a phenomenological model to explain the appearance of the
modulated phases and a microscopic Hamiltonian that captures the complete
magnetic behavior of TmB_4.Comment: 7 pages, 5 figure
Hysteretic magnetoresistance and unconventional anomalous Hall effect in the frustrated magnet TmB_4
We study TmB_4, a frustrated magnet on the Archimedean Shastry-Sutherland
lattice, through magnetization and transport experiments. The lack of
anisotropy in resistivity shows that TmB_4 is an electronically
three-dimensional system. The magnetoresistance (MR) is hysteretic at
low-temperature even though a corresponding hysteresis in magnetization is
absent. The Hall resistivity shows unconventional anomalous Hall effect (AHE)
and is linear above saturation despite a large MR. We propose that complex
structures at magnetic domain walls may be responsible for the hysteretic MR
and may also lead to the AHE
Local lattice instability and stripes in the CuO 2 plane of the La 1.85 Sr 0.15 CuO 4 system by polarized XANES and EXAFS
Temperature-dependent polarized Cu K-edge x-ray absorption has been used to investigate local structural distortions in the plane of the system. The Cu-O pair distribution shows the presence of a minority phase containing octahedra characterized by a shorter Cu-O(apical) bond (\ensuremath{\Delta}R\ensuremath{\sim}-0.1 \AA{}) and two longer Cu-O(planar) bonds (\ensuremath{\Delta}R\ensuremath{\sim}+0.08 \AA{}) and a tilting angle of 16\ifmmode^\circ\else\textdegree\fi{}\ifmmode\pm\else\textpm\fi{}2\ifmmode^\circ\else\textdegree\fi{}. The temperature-dependent distortions show a maximum around T (\ensuremath{\sim}1.) and a minimum at (\ensuremath{\sim}35 K). The data show the coexistence of two types of doped charges in different stripes in the superconducting phase
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