45 research outputs found
Anomalous Hall effect in non-collinear antiferromagnetic antiperovskite MnNiCuN
We report the anomalous Hall effect (AHE) in antiperovskite MnNiN with
substantial doping of Cu on the Ni site (i.e. MnNiCuN),
which stabilizes a noncollinear antiferromagnetic (AFM) order compatible with
the AHE. Observed on both sintered polycrystalline pieces and single
crystalline films, the AHE does not scale with the net magnetization, contrary
to the conventional ferromagnetic case. The existence of the AHE is explained
through symmetry analysis based on the AFM order in Cu doped
MnNiN. DFT calculations of the intrinsic contribution to the AHE reveal
the non-vanishing Berry curvature in momentum space due to the noncollinear
magnetic order. Combined with other attractive properties, antiperovskite
MnAN system offers great potential in AFM spintronics.Comment: Supplemental Materials not include
Momentum-Dependent Hybridization Gap and dispersive in-gap state of The Kondo Semiconductor SmB6
We report the temperature-dependent three-dimensional angle-resolved
photoemission spectra of the Kondo semiconductor SmB. We found a difference
in the temperature dependence of the peaks at the X and points, due to
hybridization between the Sm 5d conduction band and the nearly localized Sm 4f
state. The peak intensity at the X point has the same temperature dependence as
the valence transition below 120 K, while that at the point is
consistent with the magnetic excitation at Q=(0.5,0.5,0.5) below 30 K. This
suggests that the hybridization with the valence transition mainly occurs at
the X point, and the initial state of the magnetic excitation is located at the
point.Comment: 5 pages, 3 figure
Contrast of LiFeAs with isostructural, isoelectronic, and non-superconducting MgFeGe
Stoichiometric LiFeAs at ambient pressure is an 18 K superconductor while
isoelectronic MgFeGe is not, despite their extremely similar electronic
structures. To investigate possible sources of this distinctively different
superconducting behavior, we quantify the differences using first principles
density functional theory, establishing first that the Fe total 3d occupations
are identical in the two compounds. Individual 3d orbital occupations also
differ very little (). The differences in Fermi surfaces (FSs) do
not seem significant; however a redistribution of bands just above the Fermi
level does represent a possibly significant distinction. Because the bands and
FSs of LiFeAs are less in agreement with experiment than for other
iron-pnictides, we study the effects of additional exchange-correlations
effects beyond GGA (the generalized gradient approximation) by applying the
modified Becke-Johnson potential (mBJ) exchange potential, which gives much
improved bandgaps in insulators compared to GGA and might be useful for
semimetals such as the Fe-based superconductors. Overall, we conclude that the
mBJ corrections do not improve the description of LiFeAs as compared to
experiment